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KS3 SCIENCE - KS3 PHYSICS QUIZZES

KS3 PHYSICS QUIZZES

Doc B's revising for KS3 SCIENCE - Doc Brown's Physics

I appreciate SAT levels have gone, but I hope these KS3 physics Quizzes will still be of some use. Although I've already produced some combined KS3 physics quizzes, I welcome suggestions from teachers so I may produce useful compilation KS3 physics quizzes suitable for any school doing KS3 physics and any KS3 physics scheme of work. Copying of the KS3 physics quizzes is NOT permitted, but you can printout the KS3 physics questions to use in class or for homework.

The first part of the page is the most important - the links to the KS3 Physics multiple choice quizzes.

The rest of the page is lots of guidance for doc b to help design the most useful KS3 Physics quizzes


For after KS3 SCIENCE ...

GCSE 9-1 Chemistry Notes * GCSE 9-1 Biology Notes * GCSE 9-1 Physics Notes



The KS3 Physics Multiple Choice Questions

The KS3 Physics Questions are selected at random from big databases.

NOTE (1) <= back on the link bar returns you to the previous web page.

(2) Don't use the usual refresh button on the upper browser to repeat the quiz, use the    REPEAT QUIZ - fresh Q's    on the quiz link bar.

(3) A small proportion of these KS3 physics questions are deliberately very challenging and more like GCSE level, but only the odd one! and most cover the full range of ability of KS3 science students.


Multiple choice question KS3 PHYSICS Quizzes

  1. KS3 Physics Quiz - 7I Energy resources QUIZ 7I on "Energy resources" Questions on examples/properties/uses of fuel combustion, non-renewable energy resources like oil/coal/gas and their formation, renewable resources like solar, wind, hydroelectric, geothermal, biomass

  2. KS3 Physics Quiz - 7J Electrical circuits QUIZ 7J on "Electrical circuits" Questions on simple circuits, circuit symbols and components, current flow and ammeter readings, useful circuits - hazards and how they work

  3. KS3 Physics Quiz - 7K Forces and their effects QUIZ 7K on "Forces and their effects" Questions on types of force and their effects, density and floating, force meters, mass and weight, friction and braking

  4. KS3 Physics Quiz - 7L The solar system and beyond QUIZ 7L on "The solar system and beyond" Questions on Sun, Earth and Moon orbits, eclipses, phases of the Moon, what causes seasonal changes, the other planets of the solar system, other stars beyond our Sun

  5. KS3 Physics Quiz - 8I Heating and cooling QUIZ 8I on "Heating and cooling" Questions on measuring temperature with thermometer, heating and cooling, expansion and contraction, heat transfer - conduction, convection and radiation, insulation to reduce heat loss, changing state gas <=> liquid <=> solid e.g. melting, boiling, freezing and condensing

  6. KS3 Physics Quiz - 8J Magnets and electromagnets QUIZ 8J on "Magnets and electromagnets" Questions on magnetic materials, north and south poles, magnetic fields, electromagnets, uses of magnets

  7. KS3 Physics Quiz - 8K Light QUIZ 8K on "Light" Questions on reflection of light, mirrors, shadows, light bending, visible spectrum

  8. KS3 Physics Quiz - 8L Sound and hearing QUIZ 8L on "Sound and hearing" Questions on sound waves, pitch/frequency, loudness/amplitude, comparing speed of light/sound, hearing - function of ear

  9. KS3 Physics Quiz - 9I Energy and electricity QUIZ 9I on "Energy and electricity" Questions on how we use energy, energy transfer using electrical circuits, cost of electricity, making electricity, how can we reduce energy waste?

  10. KS3 Physics Quiz - 9J Gravity and space QUIZ 9J on "Gravity and space" Questions on understanding gravity, mass and weight, the Solar System, planet orbits, satellites and their uses

  11. KS3 Physics Quiz - 9K Speeding up QUIZ 9K on "Speeding up" Questions on understanding the relationship between speed, distance and time, the connection between forces, speed and friction, understanding parachuting

  12. KS3 Physics Quiz - 9L Pressure and moments QUIZ 9L on "Pressure and moments" Questions on pressure, pneumatic and hydraulic systems, levers, moments and balancing situations



SEE ALSO the KS3 Science Quiz compilations

20 Question multiple choice QUIZ on  ORGANISMS, BEHAVIOUR and HEALTH

20 Question multiple choice QUIZ on CHEMICAL and MATERIAL BEHAVIOUR

20 Question multiple choice QUIZ on ENERGY, ELECTRICITY and FORCES

20 Question multiple choice QUIZ on THE ENVIRONMENT, EARTH & UNIVERSE


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National Curriculum KS3 Science PHYSICS specification

Subject content – KS3 Physics Pupils should be taught about:

KS3 physics Energy      (National Curriculum KS3 science-physics)

KS3 physics Calculation of fuel uses and costs in the domestic context

comparing energy values of different foods (from labels) (kJ)

 comparing power ratings of appliances in watts (W, kW)

 comparing amounts of energy transferred (J, kJ, kW hour)

 domestic fuel bills, fuel use and costs

fuels and energy resources.

KS3 physics Energy changes and transfers      (National Curriculum KS3 science-physics)

simple machines give bigger force but at the expense of smaller movement (and vice versa): product of force and displacement unchanged

heating and thermal equilibrium: temperature difference between two objects leading to energy transfer from the hotter to the cooler one, through contact (conduction) or radiation; such transfers tending to reduce the temperature difference: use of insulators

other processes that involve energy transfer: changing motion, dropping an object, completing an electrical circuit, stretching a spring, metabolism of food, burning fuels.

KS3 physics Changes in systems      (National Curriculum KS3 science-physics)

energy as a quantity that can be quantified and calculated; the total energy has the same value before and after a change

comparing the starting with the final conditions of a system and describing increases and decreases in the amounts of energy associated with movements, temperatures, changes in positions in a field, in elastic distortions and in chemical compositions

using physical processes and mechanisms, rather than energy, to explain the intermediate steps that bring about such changes.

KS3 physics Motion and forces      (National Curriculum KS3 science-physics)

KS3 physics Describing motion      (National Curriculum KS3 science-physics)

speed and the quantitative relationship between average speed, distance and time (speed = distance ÷ time)

the representation of a journey on a distance-time graph

relative motion: trains and cars passing one another.

KS3 physics Forces      (National Curriculum KS3 science-physics)

forces as pushes or pulls, arising from the interaction between two objects

using force arrows in diagrams, adding forces in one dimension, balanced and unbalanced forces

moment as the turning effect of a force

forces: associated with deforming objects; stretching and squashing – springs; with rubbing and friction between surfaces, with pushing things out of the way; resistance to motion of air and water

forces measured in newtons, measurements of stretch or compression as force is changed

force-extension linear relation; Hooke’s Law as a special case

work done and energy changes on deformation

non-contact forces: gravity forces acting at a distance on Earth and in space, forces between magnets and forces due to static electricity.

KS3 physics Pressure in fluids      (National Curriculum KS3 science-physics)

atmospheric pressure, decreases with increase of height as weight of air above decreases with height

pressure in liquids, increasing with depth; upthrust effects, floating and sinking

pressure measured by ratio of force over area – acting normal to any surface.

KS3 physics Balanced forces      (National Curriculum KS3 science-physics)

opposing forces and equilibrium: weight held by stretched spring or supported on a compressed surface.

KS3 physics Forces and motion      (National Curriculum KS3 science-physics)

forces being needed to cause objects to stop or start moving, or to change their speed or direction of motion (qualitative only)

change depending on direction of force and its size.

KS3 physics Waves       (National Curriculum KS3 science-physics)

KS3 physics Observed waves      (National Curriculum KS3 science-physics)

waves on water as undulations which travel through water with transverse motion; these waves can be reflected, and add or cancel – superposition.

KS3 physics Sound waves      (National Curriculum KS3 science-physics)

frequencies of sound waves, measured in hertz (Hz); echoes, reflection and absorption of sound

sound needs a medium to travel, the speed of sound in air, in water, in solids

sound produced by vibrations of objects, in loud speakers, detected by their effects on microphone diaphragm and the ear drum; sound waves are longitudinal

auditory range of humans and animals.

KS3 physics Energy and waves      (National Curriculum KS3 science-physics)

pressure waves transferring energy; use for cleaning and physiotherapy by ultra-sound; waves transferring information for conversion to electrical signals by microphone.

KS3 physics Light waves      (National Curriculum KS3 science-physics)

the similarities and differences between light waves and waves in matter

light waves travelling through a vacuum; speed of light

the transmission of light through materials: absorption, diffuse scattering and specular reflection at a surface

use of ray model to explain imaging in mirrors, the pinhole camera, the refraction of light and action of convex lens in focusing (qualitative); the human eye

light transferring energy from source to absorber leading to chemical and electrical effects; photo-sensitive material in the retina and in cameras

colours and the different frequencies of light, white light and prisms (qualitative only); differential colour effects in absorption and diffuse reflection.

KS3 physics Electricity and electromagnetism      (National Curriculum KS3 science-physics)

KS3 physics Current electricity      (National Curriculum KS3 science-physics)

electric current, measured in amperes, in circuits, series and parallel circuits, currents add where branches meet and current as flow of charge

potential difference, measured in volts, battery and bulb ratings; resistance, measured in ohms, as the ratio of potential difference (p.d.) to current

differences in resistance between conducting and insulating components (quantitative).

KS3 physics Static electricity      (National Curriculum KS3 science-physics)

separation of positive or negative charges when objects are rubbed together: transfer of electrons, forces between charged objects

the idea of electric field, forces acting across the space between objects not in contact.

KS3 physics Magnetism      (National Curriculum KS3 science-physics)

magnetic poles, attraction and repulsion

magnetic fields by plotting with compass, representation by field lines

Earth’s magnetism, compass and navigation

the magnetic effect of a current, electromagnets, D.C. motors (principles only).

KS3 physics Matter       (National Curriculum KS3 science-physics)

KS3 physics Physical changes      (National Curriculum KS3 science-physics)

conservation of material and of mass, and reversibility, in melting, freezing, evaporation, sublimation, condensation, dissolving

similarities and differences, including density differences, between solids, liquids and gases

Brownian motion in gases

diffusion in liquids and gases driven by differences in concentration

the difference between chemical and physical changes.

KS3 physics Particle model      (National Curriculum KS3 science-physics)

the differences in arrangements, in motion and in closeness of particles explaining changes of state, shape and density, the anomaly of ice-water transition

atoms and molecules as particles.

KS3 physics Energy in matter      (National Curriculum KS3 science-physics)

changes with temperature in motion and spacing of particles

internal energy stored in materials.

KS3 physics Space physics      (National Curriculum KS3 science-physics)

gravity force, weight = mass x gravitational field strength (g), on Earth g=10 N/kg, different on other planets and stars; gravity forces between Earth and Moon, and between Earth and Sun (qualitative only)

our Sun as a star, other stars in our galaxy, other galaxies

the seasons and the Earth’s tilt, day length at different times of year, in different hemispheres

the light year as a unit of astronomical distance.



AQA KS3 Physics

AQA KS3 physics 3.1 Forces

3.1.1 Speed Investigate variables that affect the speed of a toy car rolling down a slope

AQA KS3 physics Know

If the overall, resultant force on an object is non-zero, its motion changes and it slows down, speeds up or changes direction.

Skill Use the formula: speed = distance (m)/time (s) or distance-time graphs, to calculate speed.

Facts A straight line on a distance-time graph shows constant speed, a curving line shows acceleration.

The higher the speed of an object, the shorter the time taken for a journey.

Keywords

Speed: How much distance is covered in how much time.

Average speed: The overall distance travelled divided by overall time for a journey.

Relative motion: Different observers judge speeds differently if they are in motion too, so an object’s speed is relative to the observer’s speed.

Acceleration: How quickly speed increases or decreases.

AQA KS3 physics Apply

Illustrate a journey with changing speed on a distance-time graph, and label changes in motion.

Describe how the speed of an object varies when measured by observers who are not moving, or moving relative to the object.

AQA KS3 physics Extend

Suggest how the motion of two objects moving at different speeds in the same direction would appear to the other.

Predict changes in an object’s speed when the forces on it change

 

AQA KS3 physics 3.1.2 Gravity

AQA KS3 physics Explain the way in which an astronaut’s weight varies on a journey to the moon

AQA KS3 physics Know

Mass and weight are different but related. Mass is a property of the object; weight depends upon mass but also on gravitational field strength.

Every object exerts a gravitational force on every other object. The force increases with mass and decreases with distance. Gravity holds planets and moons in orbit around larger bodies.

Skill Use the formula: weight (N) = mass (kg) x gravitational field strength (N/kg).

Fact g on Earth = 10 N/kg. On the moon it is 1.6 N/kg.

Keywords

Weight: The force of gravity on an object (N).

Non-contact force: One that acts without direct contact.

Mass: The amount of stuff in an object (kg).

Gravitational field strength, g: The force from gravity on 1 kg (N/kg).

Field: The area where other objects feel a gravitational force.

AQA KS3 physics Apply

Explain unfamiliar observations where weight changes.

Draw a force diagram for a problem involving gravity.

Deduce how gravity varies for different masses and distances.

Compare your weight on Earth with your weight on different planets using the formula.

AQA KS3 physics Extend

Compare and contrast gravity with other forces.

Draw conclusions from data about orbits, based on how gravity varies with mass and distance.

Suggest implications of how gravity varies for a space mission.

 

AQA KS3 physics 3.1.3 Contact forces

AQA KS3 physics Investigate factors that affect the size of frictional or drag forces

AQA KS3 physics Know

When the resultant force on an object is zero, it is in equilibrium and does not move, or remains at constant speed in a straight line. One effect of a force is to change an object’s form, causing it to be stretched or compressed. In some materials, the change is proportional to the force applied.

Skill Sketch the forces acting on an object, and label their size and direction.

Keywords

Equilibrium: State of an object when opposing forces are balanced.

Deformation: Changing shape due to a force.

Linear relationship: When two variables are graphed and show a straight line which goes through the origin, and they can be called directly proportional.

Newton: Unit for measuring forces (N).

Resultant force: Single force which can replace all the forces acting on an object and have the same effect.

Friction: Force opposing motion which is caused by the interaction of surfaces moving over one another. It is called ‘drag’ if one is a fluid. Tension:

Force extending or pulling apart.

Compression: Force squashing or pushing together.

Contact force: One that acts by direct contact.

AQA KS3 physics Apply

Explain whether an object in an unfamiliar situation is in equilibrium.

Describe factors which affect the size of frictional and drag forces.

Describe how materials behave as they are stretched or squashed.

Describe what happens to the length of a spring when the force on it changes.

AQA KS3 physics Extend

Evaluate how well sports or vehicle technology reduces frictional or drag forces.

Describe the effects of drag and other forces on falling or accelerating objects as they move.

Using force and extension data, compare the behaviour of different materials in deformation using the idea of proportionality.

Explain how turning forces are used in levers.

 

AQA KS3 physics 3.1.4 Pressure

Investigate how pressure from your foot onto the ground varies with different footwear

AQA KS3 physics Know

Pressure acts in a fluid in all directions. It increases with depth due to the increased weight of fluid, and results in an upthrust. Objects sink or float depending on whether the weight of the object is bigger or smaller than the upthrust.

Different stresses on a solid object can be used to explain observations where objects scratch, sink into or break surfaces.

Skill Use the formula: fluid pressure, or stress on a surface = force (N)/area (m2).

Keywords

Fluid: A substance with no fixed shape, a gas or a liquid.

Pressure: The ratio of force to surface area, in N/ m2, and how it causes stresses in solids.

Upthrust: The upward force that a liquid or gas exerts on a body floating in it.

Atmospheric pressure: The pressure caused by the weight of the air above a surface.

AQA KS3 physics Apply

Use diagrams to explain observations of fluids in terms of unequal pressure.

Explain why objects either sink or float depending upon their weight and the upthrust acting on them.

Explain observations where the effects of forces are different because of differences in the area over which they apply.

Given unfamiliar situations, use the formula to calculate fluid pressure or stress on a surface

AQA KS3 physics Extend

Use the idea of pressure changing with depth to explain underwater effects.

Carry out calculations involving pressure, force and area in hydraulics, where the effects of applied forces are increased.

Use the idea of stress to deduce potential damage to one solid object by another.
 

AQA KS3 physics 3.2 Electromagnets

AQA KS3 physics 3.2.1 Voltage and resistance

Compare the voltage drop across resistors connected in series in a circuit

AQA KS3 physics Know

We can model voltage as an electrical push from the battery, or the amount of energy per unit of charge transferred through the electrical pathway.

In a series circuit, voltage is shared between each component.

In a parallel circuit, voltage is the same across each loop.

Components with resistance reduce the current flowing and shift energy to the surroundings.

Skill Calculate resistance using the formula: resistance (Ω) = potential difference (V) ÷ current (A).

Keywords

Potential difference (voltage): The amount of energy shifted from the battery to the moving charge, or from the charge to circuit components, in volts (V).

Resistance: A property of a component, making it difficult for charge to pass through, in ohms (Ω).

Electrical conductor: A material that allows current to flow through it easily, and has a low resistance.

Electrical insulator: A material that does not allow current to flow easily, and has a high resistance.

AQA KS3 physics Apply

Draw a circuit diagram to show how voltage can be measured in a simple circuit.

Use the idea of energy to explain how voltage and resistance affect the way components work.

Given a table of voltage against current. Use the ratio of voltage to current to determine the resistance.

Use an analogy like water in pipes to explain why part of a circuit has higher resistance.

AQA KS3 physics Extend

Predict the effect of changing the rating of a battery or a bulb on other components in a series or parallel circuit.

Justify the sizes of voltages in a circuit, using arguments based on energy.

Draw conclusions about safety risks, from data on voltage, resistance and current.
 

AQA KS3 physics 3.2.2 Current

Compare and explain current flow in different parts of a parallel circuit

AQA KS3 physics Know

Current is a movement of electrons and is the same everywhere in a series circuit.

Current divides between loops in a parallel circuit, combines when loops meet, lights up bulbs and makes components work.

Around a charged object, the electric field affects other charged objects, causing them to be attracted or repelled.

The field strength decreases with distance.

Fact Two similarly charged objects repel, two differently charged objects attract.

Keywords

Negatively charged: An object that has gained electrons as a result of the charging process.

Positively charged: An object that has lost electrons as a result of the charging process.

Electrons: Tiny particles which are part of atoms and carry a negative charge.

Charged up: When materials are rubbed together, electrons move from one surface to the other.

Electrostatic force: Non-contact force between two charged objects.

Current: Flow of electric charge, in amperes (A).

In series: If components in a circuit are on the same loop.

In parallel: If some components are on separate loops.

Field: The area where other objects feel an electrostatic force.

AQA KS3 physics Apply

Describe  how current changes in series and parallel circuits when components are changed.

Turn circuit diagrams into real series and parallel circuits, and vice versa.

Describe what happens when charged objects are placed near to each other or touching.

Use a sketch to describe how an object charged positively or negatively became charged up.

AQA KS3 physics Extend

Compare the advantages of series and parallel circuits for particular uses.

Evaluate a model of current as electrons moving from the negative to the positive terminal of a battery, through the circuit.

Suggest ways to reduce the risk of getting electrostatic shocks.
 

AQA KS3 physics 3.2.3 Electromagnets

Investigate ways of varying strength of an electromagnet

AQA KS3 physics Know

An electromagnet uses the principle that a current through a wire causes a magnetic field.

Its strength depends on the current, the core and the number of coils in the solenoid.

Fact The magnetic field of an electromagnet decreases in strength with distance.

Keywords

Electromagnet: A non-permanent magnet turned on and off by controlling the current through it.

Solenoid: Wire wound into a tight coil, part of an electromagnet.

Core: Soft iron metal which the solenoid is wrapped around.

AQA KS3 physics Apply

Use a  diagram to explain how an electromagnet can be made and how to change its strength.

Explain the choice of electromagnets or permanent magnets for a device in terms of their properties.
 

AQA KS3 physics Extend

Critique the design of a device using an electromagnet and suggest improvements.

Suggest how bells, circuit breakers and loudspeakers work, from diagrams.
 

AQA KS3 physics 3.2.4 Magnetism

Explore the magnetic field pattern around different types or combinations of magnets

AQA KS3 physics Know

Magnetic materials, electromagnets and the Earth create magnetic fields which can be described by drawing field lines to show the strength and direction.

The stronger the magnet, and the smaller the distance from it, the greater the force a magnetic object in the field experiences.

Facts Two ‘like’ magnetic poles repel and two ‘unlike’ magnetic poles attract.

Field lines flow from the north-seeking pole to the south-seeking pole.

Keywords

Magnetic force: Non-contact force from a magnet on a magnetic material.

Permanent magnet: An object that is magnetic all of the time.

Magnetic poles: The ends of a magnetic field, called north-seeking (N) and south-seeking poles (S).

AQA KS3 physics Apply

Use the idea of field lines to show how the direction or strength of the field around a magnet varies.

Explain observations about navigation using Earth’s magnetic field.

AQA KS3 physics Extend

Predict the pattern of field lines and the force around two magnets placed near each other.

Predict how an object made of a magnetic material will behave if placed in or rolled through a magnetic field.
 

 

AQA KS3 physics 3.3 Energy

AQA KS3 physics 3.3.1 Energy costs

AQA KS3 physics Compare the running costs of fluorescent and filament light bulbs

AQA KS3 physics Know

We pay for our domestic electricity usage based on the amount of energy transferred.

Electricity is generated by a combination of resources which each have advantages and disadvantages.

Calculate the cost of home energy usage, using the formula: cost = power (kW ) x time (hours) x price (per kWh).

Fact Food labels list the energy content of food in kilojoules (kJ).

Keywords

Power: How quickly energy is transferred by a device (watts).

Energy resource: Something with stored energy that can be released in a useful way.

Non-renewable: An energy resource that cannot be replaced and will be used up.

Renewable: An energy resource that can be replaced and will not run out. Examples are solar, wind, waves, geothermal and biomass.

Fossil fuels: Non-renewable energy resources formed from the remains of ancient plants or animals. Examples are coal, crude oil and natural gas.

AQA KS3 physics Apply

Compare the amounts of energy transferred by different foods and activities.

Compare the energy usage and cost of running different home devices.

Explain the advantages and disadvantages of different energy resources.

Represent the energy transfers from a renewable or non-renewable resource to an electrical device in the home.

AQA KS3 physics Extent

Evaluate the social, economic and environmental consequences of using a resource to generate electricity, from data.

Suggest actions a government or communities could take in response to rising energy demand.

Suggest ways to reduce costs, by examining data on a home energy bill.
 

AQA KS3 physics 3.3.2 Energy transfer

AQA KS3 physics Explain the energy transfers in a hand-crank torch

AQA KS3 physics Know

We can describe how jobs get done using an energy model where energy is transferred from one store at the start to another at the end.

When energy is transferred, the total is conserved, but some energy is dissipated, reducing the useful energy.

Keywords

Thermal energy store: Filled when an object is warmed up.

Chemical energy store: Emptied during chemical reactions when energy is transferred to the surroundings.

Kinetic energy store: Filled when an object speeds up.

Gravitational potential energy store: Filled when an object is raised.

Elastic energy store: Filled when a material is stretched or compressed.

Dissipated: Become spread out wastefully.

AQA KS3 physics Apply

Describe how the energy of an object depends on its speed, temperature, height or whether it is stretched or compressed.

Show how energy is transferred between energy stores in a range of real-life examples.

Calculate the useful energy and the amount dissipated, given values of input and output energy.

Explain how energy is dissipated in a range of situations.

AQA KS3 physics Extend

Compare the percentages of energy wasted by renewable energy sources.

Explain why processes such as swinging pendulums or bouncing balls cannot go on forever, in terms of energy.

Evaluate analogies and explanations for the transfer of energy.
 

AQA KS3 physics 3.3.3 Work

AQA KS3 physics Explain how an electric motor raising a weight is doing work

AQA KS3 physics Know

Work is done and energy transferred when a force moves an object.

The bigger the force or distance, the greater the work.

Machines make work easier by reducing the force needed.

Levers and pulleys do this by increasing the distance moved, and wheels reduce friction.

Keywords

Work: The transfer of energy when a force moves an object, in joules.

Lever: A type of machine which is a rigid bar that pivots about a point.

Input force: The force you apply to a machine.

Output force: The force that is applied to the object moved by the machine.

Displacement: The distance an object moves from its original position.

Deformation: When an elastic object is stretched or squashed, which requires work.

AQA KS3 physics Apply

Draw a diagram to explain how a lever makes a job easier.

Compare the work needed to move objects different distances.

AQA KS3 physics Extend

Use the formula: work done (J) = force (N) x distance moved (m) to compare energy transferred for objects moving horizontally.

Compare and contrast the advantages of different levers in terms of the forces need and distance moved.
 

AQA KS3 physics 3.3.4 Heating and cooling

Investigate how to prevent heat loss by conduction, convection and radiation

AQA KS3 physics Know

The thermal energy of an object depends upon its mass, temperature and what it’s made of.

When there is a temperature difference, energy transfers from the hotter to the cooler object.

Thermal energy is transferred through different pathways, by particles in conduction and convection, and by radiation.

Keywords

Thermal conductor: Material that allows heat to move quickly through it.

Thermal insulator: Material that only allows heat to travel slowly through it.

Temperature: A measure of the motion and energy of the particles.

Thermal energy: The quantity of energy stored in a substance due to the vibration of its particles.

Conduction: Transfer of thermal energy by the vibration of particles.

Convection: Transfer of thermal energy when particles in a heated fluid rise.

Radiation: Transfer of thermal energy as a wave.

AQA KS3 physics Apply

Explain observations about changing temperature in terms of energy transfer.

Describe how an object’s temperature changes over time when heated or cooled.

Explain how a method of thermal insulation works in terms of conduction, convection and radiation.

Sketch diagrams to show convection currents in unfamiliar situations.

AQA KS3 physics Extend

Sketch a graph to show the pattern of temperature change against time.

Evaluate a claim about insulation in the home or for clothing technology.

Compare and contrast the three ways that energy can be moved from one place to another by heating.
 

AQA KS3 physics 3.4 Waves

AQA KS3 physics 3.4.1 Sound

Relate changes in the shape of an oscilloscope trace to changes in pitch and volume

AQA KS3 physics Know

Sound consists of vibrations which travel as a longitudinal wave through substances.

The denser the medium, the faster sound travels.

The greater the amplitude of the waveform, the louder the sound.

The greater the frequency (and therefore the shorter the wavelength), the higher the pitch.

Facts

Sound does not travel through a vacuum.

The speed of sound in air is 330 m/s, a million times slower than light.

Keywords

Vibration: A back and forth motion that repeats.

Longitudinal wave: Where the direction of vibration is the same as that of the wave.

Volume: How loud or quiet a sound is, in decibels (dB).

Pitch: How low or high a sound is. A low (high) pitch sound has a low (high) frequency.

Amplitude: The maximum amount of vibration, measured from the middle position of the wave, in metres.

Wavelength: Distance between two corresponding points on a wave, in metres.

Frequency: The number of waves produced in one second, in hertz.

Vacuum: A space with no particles of matter in it. Oscilloscope:

Device able to view patterns of sound waves that have been turned into electrical signals.

Absorption: When energy is transferred from sound to a material.

Auditory range: The lowest and highest frequencies that a type of animal can hear.

Echo: Reflection of sound waves from a surface back to the listener.

AQA KS3 physics Apply

Explain observations where sound is reflected, transmitted or absorbed by different media.

Explain observations of how sound travels using the idea of a longitudinal wave.

Describe the amplitude and frequency of a wave from a diagram or oscilloscope picture.

Use drawings of waves to describe how sound waves change with volume or pitch.

AQA KS3 physics Extend

Suggest the effects of particular ear problems on a person’s hearing.

Evaluate the data behind a claim for a sound creation or blocking device, using the properties of sound waves.

Use diagrams to compare the waveforms a musical instrument makes when playing different pitches or volumes.
 

 

AQA KS3 physics 3.4.2 Light

Use ray diagrams to model how light passes through lenses and transparent materials

AQA KS3 physics Know

When a light ray meets a different medium, some of it is absorbed and some reflected.

For a mirror, the angle of incidence equals the angle of reflection.

The ray model can describe the formation of an image in a mirror and how objects appear different colours.

When light enters a denser medium it bends towards the normal; when it enters a less dense medium it bends away from the normal.

Refraction through lenses and prisms can be described using a ray diagram as a model.

Skill Construct ray diagrams to show how light reflects off mirrors, forms images and refracts.

Facts

Light travels at 300 million metres per second in a vacuum.

Different colours of light have different frequencies.

Keywords

Incident ray: The incoming ray.

Reflected ray: The outgoing ray.

Normal line: From which angles are measured, at right angles to the surface.

Angle of reflection: Between the normal and reflected ray.

Angle of incidence: Between the normal and incident ray.

Refraction: Change in the direction of light going from one material into another.

Absorption: When energy is transferred from light to a material.

Scattering: When light bounces off an object in all directions.

Transparent: A material that allows all light to pass through it.

Translucent: A material that allows some light to pass through it.

Opaque: A material that allows no light to pass through it.

Convex lens: A lens that is thicker in the middle which bends light rays towards each other.

Concave lens: A lens that is thinner in the middle which spreads out light rays.

Retina: Layer at the back of the eye with light detecting cells and where an image is formed.

AQA KS3 physics Apply

Use ray diagrams of eclipses to describe what is seen by observers in different places.

Explain observations where coloured lights are mixed or objects are viewed in different lights.

Use ray diagrams to describe how light passes through lenses and transparent materials.

Describe how lenses may be used to correct vision.

AQA KS3 physics Extend

Use a ray diagram to predict how an image will change in different situations.

Predict whether light will reflect, refract or scatter when it hits the surface of a given material.

Use ray diagrams to explain how a device with multiple mirrors works.
 

AQA KS3 physics 3.4.3 Wave effects

Relate the impact of different types of waves on living cells to their frequency & the energy carried by the wave

AQA KS3 physics Know

When a wave travels through a substance, particles move to and fro.

Energy is transferred in the direction of movement of the wave.

Waves of higher amplitude or higher frequency transfer more energy.

Keywords

Ultrasound: Sound waves with frequencies higher than the human auditory range.

Ultraviolet (UV): Waves with frequencies higher than light, which human eyes cannot detect.

Microphone: Turns the pressure wave of sound hitting it into an electrical signal.

Loudspeaker: Turns an electrical signal into a pressure wave of sound.

Pressure wave: An example is sound, which has repeating patterns of high-pressure and low-pressure regions.

AQA KS3 physics Apply

Explain differences in the damage done to living cells by light and other waves, in terms of their frequency.

Explain how audio equipment converts sound into a changing pattern of electric current.

AQA KS3 physics Extend

Suggest reasons why sound waves can agitate a liquid for cleaning objects, or massage muscles for physiotherapy.

Evaluate electricity production by wave energy using data for different locations and weather conditions.
 

 

AQA KS3 physics 3.4.4 Wave properties

Use the wave model to explain observations of the reflection, absorption and transmission of waves

AQA KS3 physics Know

A physical model of a transverse wave demonstrates it moves from place to place, while the material it travels through does not, and describes the properties of speed, wavelength and reflection.

Keywords

Waves: Vibrations that transport energy from place to place without transporting matter.

Transverse wave: Where the direction of vibration is perpendicular to that of the wave.

Transmission: Where waves travel through a medium rather than be absorbed or reflected.

AQA KS3 physics Apply

Describe  the properties of different longitudinal and transverse waves.

Use the wave model to explain observations of the reflection, absorption and transmission of a wave.

AQA KS3 physics Extend

Compare and contrast the properties of sound and light waves.

Suggest what happens when two waves combine.
 

 



OCR Twenty First Century Science knowledge and understanding expected before GCSE Physics

Chapter P1 Radiation and waves

What you should have learned and experienced from KS3 science about light, sound, and waves ...

observed waves on water, spring, and strings

know the meaning of the terms longitudinal, transverse, superposition, and frequency, in the context of waves

know that sound waves are longitudinal and need a medium to travel through and that sound travels at different speeds in solids, in water, and in air

know that sound is produced when objects vibrate and that sound waves are detected by the vibrations they cause

know that light travels at a very high speed and can pass through a vacuum

know some of the similarities and differences between light waves and waves in matter

be able to use a ray model of light to describe and explain reflection in mirrors, refraction and dispersion by glass and the action of convex lenses

know that light incident on a surface may be absorbed, scattered, or reflected, and that light transfers energy from a source to an absorber, where it may cause a chemical or electrical effect.

 

Chapter P2 Sustainable energy

What you should have learned and experienced from KS3 science about energy ...

compared energy uses and costs in domestic contexts, including calculations using a variety of units

considered a variety of processes that involve transferring energy, including heating, changing motion, burning fuels and changing position in a field

 

Chapter P3 Electric circuits

What you should have learned and experienced from KS3 science about light, sound, and waves ...

be familiar with the basic properties of magnets, and use these to explain and predict observations

know that there is a magnetic field close to any wire carrying an electric current

be aware of the existence of electric charge, and understand how simple electrostatic phenomena can be explained in terms of the movement of electrons between and within objects

understand the idea of an electric circuit (a closed conducting loop containing a battery) that conducts an electric current and be able to predict the current in branches of a parallel circuit

understand the idea of as a measure of the ‘strength’ of a battery or power supply

know that electrical resistance is measured in ohms and can be calculated by dividing the voltage across the component by the current through it

know that the power ratings of electrical appliances are related to the rate at which the appliances transfers energy.

 

Chapter P4 Explaining motion

What you should have learned and experienced from KS3 science about force and motion ...

describe motion using words and with distance–time graphs

use the relationship average speed = distance ÷ time

identify the forces when two objects in contact interact; pushing, pulling, squashing, friction, turning

use arrows to indicate the different forces acting on objects, and predict the net force when two or more forces act on an object

know that the forces due to gravity, magnetism and electric charge are all non-contact forces

understand how the forces acting on an object can be used to explain its motion.

 

Chapter P5 Radioactive materials

What you should have learned and experienced from KS3 science about ? ...

recall that in each atom its electrons are arranged at different distances from the nucleus

recall that gamma rays are emitted from the nuclei of atoms

be able to describe how ionising radiation can have hazardous effects, notably on human bodily tissues.

 

Chapter P6 Matter – models and explanations

What you should have learned and experienced from KS3 science about matter and particles ...

be able to use a particulate model of matter to explain states of matter and changes of state

have investigated stretching and compressing materials and identifying those that obey Hooke’s law

be able to describe how the extension or compression of an elastic material changes as a force is applied, and make a link between the work done and energy transfer during compression or extension

have investigated pressure in liquids and related this to floating and sinking

be able to relate atmospheric pressure to the weight of air overhead.

 


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 Doc Brown's Revision  KS3 Science KS3 PHYSICS Unit 7I Energy resources

KS3 Physics: About the unit

In this unit pupils:

  are introduced to the concept of energy in the context of fuels as convenient and therefore valuable sources

  consider the nature and origin of fossil fuels and renewable sources of energy and how their use has implications for the environment

  consolidate and extend their ideas about energy resources for living things: food for people and sunlight for plants

  link the energy resources to the role of the Sun as the ultimate source of most of the Earth’s energy resources

In scientific enquiry pupils:

  recognise hazards and take safety precautions

  decide what variables are relevant and how to control these to make fair comparisons

  consider the reasons for repeating measurements and observations

  use the Bunsen burner and thermometers safely and effectively

  make measurements of volume, mass and temperature

  investigate the energy resource in foods, controlling relevant variables

KS3 Physics:  Note on the teaching of energy

This unit provides an introduction to energy through the idea of foods and fuels as energy resources. The term ‘resource’ is used in preference to ‘source’ to try to encourage the idea that energy is not just a kind of stuff, like fuel. Energy transfer is associated with change, in particular changes that can perform useful tasks, as a first step towards more formal understanding. This enables pupils to make connections between apparently disparate phenomena, as contexts are drawn from across the sciences, eg burning fuel, movement, eating food and plant growth. Pupils can begin to distinguish energy from stuff (the energy resource) and from linked concepts, eg force, power (the rate of transferring energy) and activity. A common misconception is that activity gives you energy because it makes you healthier – and so more able to do more activity.

KS3 Physics:  Where the unit fits in

This unit introduces pupils to a topic which may be new to them, although it has links with work done in key stage 2. It builds on ideas introduced in unit 6A ‘Interdependence and adaptation’ (green plants need light), unit 6D ‘Reversible and irreversible changes’ (burning), unit 6G ‘Changing circuits’ (electrical conduction) and unit 4C ‘Keeping warm’ (temperature; thermal insulation) in the key stage 2 scheme of work.

In unit 8I ‘Heating and cooling’, pupils will study energy transfer and change of state, and use particle explanations. In unit 9I ‘Energy and electricity’, pupils will study energy transformations and energy conservation.

This unit relates to unit 7A(ii) ‘Understanding materials (resistant materials)’ in the design and technology scheme of work. There are opportunities for citizenship education in this unit, in dealing with energy-supply issues.

KS3 Physics: Expectations

At the end of this unit

in terms of scientific enquiry

most pupils will: plan a fair comparison of the energy output of a range of fuels or foods; control relevant variables; reduce error by repeating readings; comment on the accuracy of results; find information from selected secondary sources about fuels and energy devices; produce rules for the safe operation of a Bunsen burner

some pupils will not have made so much progress and will: make a fair comparison of the energy output of a range of fuels or foods and with help produce a bar chart or line graph of results; use information from a secondary source in reporting on fuels and other energy sources; use a Bunsen burner safely

some pupils will have progressed further and will: compare the effectiveness of different energy-transforming appliances, eg camping stoves, windmills; select secondary sources to provide information about the use of fuels or other energy sources

in terms of physical processes

most pupils will: state that fuels release energy when burnt and describe how renewable energy resources can be used to generate electricity and provide heating; explain why conservation of fuels is important; identify energy transfers within a range of systems including those involving living things

some pupils will not have made so much progress and will: name a range of fuels used domestically and in industry and some renewable energy resources; give examples of how to save fuels; identify energy transfers in some systems

some pupils will have progressed further and will: compare the advantages and limitations of a range of energy resources and give examples of how to use fuel economically; describe energy transfer links between the Sun, energy resources and themselves

KS3 Physics:  Prior learning

It is helpful if pupils:

  have experience of burning materials

  know that plants and animals need food for growth and that plants need sunlight to grow

KS3 Physics: Health and safety

Risk assessments are required for any hazardous activity. In this unit pupils:

  plan an investigation into the burning of fuels

  burn a variety of foods

Model risk assessments used by most employers for normal science activities can be found in the publications listed in the Teacher’s guide. Teachers need to follow these as indicated in the guidance notes for the activities, and consider what modifications are needed for individual classroom situations.

KS3 Physics: Language for learning

Through the activities in this unit pupils will be able to understand, use and spell correctly:

  words with similar but distinct meanings, eg energy, activity, force, power, fuel

  words and phrases relating to scientific enquiry, eg accuracy, control of variables, reliability of results, repeat reading

Through the activities pupils could:

  find information using contents, index, glossary, key words, hotlinks, etc

  group sentences into paragraphs with subheadings as appropriate

  develop ideas and plans into continuous text

KS3 Physics: Resources

Resources include:

  ‘spirit burners’ and alcohols or a similar range of fuels

  samples of food, eg dry breakfast cereals, crispbread, toast

  unpainted tin lids

  videos and other secondary sources of information on fossil fuels and renewable energy sources

  aluminium ‘takeaway’ trays or similar for making solar panels

  samples of coal and oil

  solar cell

  role cards for class debate on issues related to energy use

KS3 Physics: Out-of-school learning

Pupils could:

  use the internet to find out about fossil fuels and renewable energy sources

  collect magazine pictures to illustrate use of energy resources

    KS3 Physics: Why are fuels useful?

   that fuels are substances which burn to release energy

   Review pupils’ understanding of the word ‘fuel’.

   Ask pupils What fuels can you name and what do we use them for? This leads to a general statement that when fuels burn they make things happen. Introduce the definition of ‘energy’ as what burning fuels release to make things happen.

  identify some common fuels

  identify fuels as sources of light, heat and movement, all of which can be called energy

   Energy is not covered in the key stage 2 programme of study, but all pupils will have used the word in a variety of contexts.

   how to use a Bunsen burner and heating apparatus safely

   how to use and read a Celsius-scale thermometer with care

   to decide which factors need to be controlled to make a fair comparison

   Demonstrate and then instruct pupils in the safe use of the Bunsen burner and associated heating equipment. Tell pupils they are going to explore the output from natural gas fuel with the Bunsen burner set at different flames by measuring the temperature rise of a fixed volume of water in a beaker. Ask pupils to decide which factors they should keep the same in order to make a fair comparison.

  use a Bunsen burner safely and recognise the need for eye protection and other safety precautions

  use a thermometer accurately

  make a fair comparison of the output of different flames

   Pupils could be issued with a ‘licence’ to use a Bunsen burner, which could be revoked for rule infringements.

   The concept of temperature is developed in unit 8I ‘Heating and cooling’.

   to consider factors involved in making a fair comparison between different fuels

   Ask for examples of uses of different fuels. Discuss with pupils how to carry out a fair test of which is the best fuel, eg liquid fuels (alcohols) in ‘spirit burners’, or solid fuels for camping stoves. Burn the fuel and record the temperature rise of water as a cooperative whole-class demonstration. Ask pupils to discuss how good they think the results are. Encourage pupils to consider factors which have not been controlled that may affect the results, and to consider possible errors of measurements.

  produce a chart which shows temperature rise from a range of fuels

  describe how to improve accuracy by repeating readings or by controlling variables more carefully

   Discuss the hazards and precautions with the class. They will have the opportunity to plan and carry out a similar comparison, for foods, later in the unit.

Safety  

employer’s risk assessments on the use of fuels should be followed. Eye protection should be worn. Small quantities should be used, and kept clear of stock supplies. Do not allow unsupervised use of fuels. Do not use petrol

    KS3 Physics: What are fossil fuels?

   that coal, mineral oil and natural gas are examples of fossil fuels, which are formed from organic and non-renewable materials over many millions of years

   about the need for fuel conservation

   to find information using contents, index, glossary, key words, hotlinks

   to group sentences into paragraphs with subheadings as appropriate

   to plan and develop ideas and lines of thinking into continuous text

   Show pupils fossil fuels, eg pieces of coal, sealed samples of artificial crude oil, and ask them what they know of their origins and that of natural gas. Build on this by:

    – providing appropriate resources, eg video of how fossil fuels were formed, their extraction and present-day uses; a range of secondary sources including ICT (CD-ROM or internet)

    – setting a clear task to present some aspects of the topic, eg a poster on the formation of fossil fuels or how our use of fossil fuels has changed; a simple drama or narrative such as ‘From trees and T-Rex to fossil fuels’, based on information from the video or other secondary sources

    – discussing a question about the future use of fuel, eg As these fuels are non-renewable, will there be enough fuel in the future? Discuss what could be done and how pupils can contribute to conserving fuel supplies. Focus on what that could mean for pupils’ lifestyles, eg walking to school, wearing warmer clothes, going to bed at dusk. Ask pupils to prepare a leaflet to explain the issues to year 6 pupils

  name several fossil fuels and explain why they are described as fossil

  explain that fossil fuel reserves are limited because they are non-renewable

  provide coherent accounts of the formation or use of fossil fuels by writing, pictures or other means, such as class wall display

  contribute to a discussion on fossil fuels

   The distinction between ‘conservation of energy’ and ‘conservation of energy resources’ is explained in unit 9I ‘Energy and electricity’.

   Pupils may need support to engage in productive discussion, eg prompt questions on cards.

   Some pupils may prefer a report that is primarily image based, eg computer clip art or images from magazines.

   This work could be linked with unit 8 ‘Public information systems’ in the ICT scheme of work.

 KS3 Physics: What are renewable energy resources?

   that renewable energy resources include wind, waves, running water, sunlight, biomass and some geothermal sources

   how a device works using a renewable energy resource

   that renewable energy resources can be used to generate electricity

   Some pupils will probably have suggested renewable resources in the previous discussion. Ask pupils what they know, and support this, eg show a video of the range of types of renewable energy resources.

   Demonstrate the use of a device and discuss the role of the renewable resource, eg solar cells transform solar energy into electrical energy by driving a small motor, solar panels transfer solar energy to water, running water on a turbine, etc.

  identify the main renewable energy resources

  explain the term ‘renewable energy resource’

  describe the operation of a device driven by a renewable energy source, eg solar cell to generate electricity

   Pupils may have seen wind farms, hydroelectric generating stations or water-power installations.

   to make and explain predictions

   to find patterns in results

   to decide whether evidence supports their predictions

   Show pupils images of solar panels and help them to identify key features, eg large surface, black colour, contain water.

   Tell them they are going to use black and silver trays of various sizes, eg aluminium ‘takeaway’ containers, containing the water and covered with clingfilm, to see which rises in temperature by the greatest amount over the length of the lesson if left in the sun. Use a microscope bench lamp if there is no sunlight. A datalogger could be connected in order to look at the relative changes in temperatures dynamically. Ask pupils to decide what factors they need to control to make a fair comparison and to predict which of their containers will show the greatest temperature rise, giving their reasons. Discuss their results with them and ask them to think again about the predictions they made and, if appropriate, why they weren’t supported by the evidence.

  give a reason for the prediction made

  evaluate evidence collected, saying whether it supports the prediction

   This is intended as a quick comparison; pupils may identify limitations in the arrangements. The description of differential absorption of radiation by black and silver objects is not expected.

   Collaboration with the design and technology department could develop the design aspect of this work.

   An ‘energy resources kit’ with solar panels and model windmills would be useful.

   about the ways in which scientists work on developing energy devices, etc

   to use secondary sources of information as the basis for creative thought about an energy device or resource

   to contribute and evaluate the contribution of others to the discussion

   Provide pupils with access to up-to-date resources on energy provision and the work of scientists in developing these. Ask them to propose a useful device for the future. Encourage creative approaches, but based on science, eg giant windmills, solar collectors in space. This work could then be used to generate discussion on the pros and cons of renewable energy sources. The discussion could be extended to compare the needs and current energy use of western and less-developed nations.

  make presentations, eg through oral or written descriptions, of an energy device or resource for the future

  make a written generalisation about energy resources after a discussion, eg wood is a useful energy resource in many parts of the world

 

    KS3 Physics: Checking progress

   to synthesise what they know about energy and energy resources

   Brainstorm pupils’ understanding of the word ‘energy’, or ask them to work in pairs to write an answer to What is energy? Summarise the contributions by associating energy with changes.

   Help pupils construct a spider diagram, or concept map, covering the range of renewable and non-renewable fuels, their uses, advantages and disadvantages.

  state in their own words the idea that energy is associated with changes

  link key ideas, eg in summary, spider diagram, concept map

   Help pupils distinguish energy from activity, force and power.

    KS3 Physics: How do living things use energy?

   that we (and all living things) need energy for every activity

   that food is the energy source of animals

   that energy is measured in joules

   Review with pupils their ideas about food as the energy resource for plants and animals. This will have been covered at key stage 2, although the word ‘energy’ will not have been used. Link this use of the word ‘energy’ to its use in situations they have just studied.

   Use pupils’ knowledge of ‘calorie counts’ for slimming or body-building to introduce the idea of measuring energy input. Introduce the joule as the unit of energy. Demonstrate that it is quite a small unit, eg lifting an apple by 1 metre takes about 1 joule of energy. Look at the energy ratings of food, eg a chocolate bar. Ask pupils to consider the question If you ate the chocolate bar how high would you have to lift the apple before all the energy is used up? Tell them about the famous physicist John Tyndall, who worked out that the energy he needed to climb the Matterhorn was contained in a ham sandwich, so that was all the food he took with him.

  know that living creatures need energy to live

  identify the energy contents of a sample of food, eg from a label

   Teachers will be aware of the need for sensitivity in discussing slimming and diet.

   Pupils may think that exercise gives them energy, because of the link with health. Stress that exercise is an activity, and like others requires an energy input.

   Pupils will learn about the need for a balanced diet in unit 8A ‘Food and digestion’. This unit concentrates on the ‘energy food’ types, eg sugars, carbohydrates and fats.

   to apply the procedures used with fuels to compare the energy outputs of foods

   to repeat readings to improve results

   to control relevant variables

   to compare results and consider reasons for differences

   Ask pupils in groups to investigate the energy resource in foods, eg breakfast cereals, snack foods, crispbread and marshmallow, by burning them and measuring the rise in temperature of some water. To help pupils plan, remind them of the fuel enquiry at the beginning of this unit.

   Draw together results from different groups and ask pupils to suggest how results could be presented so that those of different groups could be compared. Ask pupils for results which do not fit the overall pattern and to suggest reasons for this.

  describe how they have carried out a comparison of foods, making sure the comparison was fair

  produce and present records of temperature rise to compare energy output of different foods

  evaluate reliability of their results compared with other groups, eg better control of heating, less heat ‘lost’

Safety

avoid peanuts if pupils are known
to suffer allergic reactions to them

– pupils should be reminded of the safety precautions used in the fuels enquiry earlier

– pupils should wear eye protection. This activity can be smelly and smoky. Check ventilation.

   that light is the energy source of green plants

   Ask pupils where the plants that produced the burnt foods get their energy from. Remind them of plants’ need for light to grow. This will help elicit pupils’ knowledge of how plants acquire energy for growth. Pupils will probably recall exceptions, eg carnivorous plants, fungi. Reinforce this by devising food chains for typical habitats and trace the energy source back to sunlight.

  draw a food chain and extend it to show the link to sunlight and to themselves

   Pupils will study the difference between temperature and energy in unit 8I ‘Heating and cooling’.

   Many pupils think that plant food is in the fertilisers. Photosynthesis is covered in unit 9C ‘Plants and photosynthesis’.

    KS3 Physics: Reviewing work

   to relate use of energy resources to effects on the environment

   to use their knowledge in addressing a moral or social issue

   that the Sun is the energy source of almost all the Earth’s energy resources

   Consolidate the learning of this unit by:

    – setting up a class debate introducing the moral and social issues of energy use in the context of application of their scientific understanding. This could involve the use of ‘role cards’, eg the views of scientists of different specialisms, of consumers, members of conservation organisations and those concerned with developing countries, or

    – extending the ‘energy story’ from key stage 2 by asking pupils to develop food chain diagrams so that they can show the network of energy from the Sun to a wide range of foods, fuels and devices and to all aspects of pupils’ lives

  contribute a view or appropriate evidence to the debate/role play

  describe, eg in an energy diagram, how energy from the Sun links to everyday activities, eg a car ride to school

   The chemical effects of fossil fuel burning are covered in unit 9G ‘Environmental chemistry’.

   Pupils will have constructed food chains in key stage 2. Food webs are introduced in unit 7C ‘Environment and feeding relationships’.

   The Sun as a star is covered in unit 7L ‘The solar system and beyond’.

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 Doc Brown's Revision  KS3 Science KS3 PHYSICS Unit 7J Electrical circuits

KS3 Physics: About the unit

In this unit pupils:

  consolidate and extend their ideas about circuits

  use concepts of electric current and energy transfer to explain the working of circuits

  explain patterns in the measurements of current and voltage

  use the concept of resistance qualitatively

  build circuits in which current flow is usefully controlled

  consider the hazards of electricity for humans

In scientific enquiry pupils:

  explore early ideas about electric current

  model current in a variety of ways

  plan safe procedures and recognise hazards

  use ammeters to measure current

Note on the teaching of energy

This unit applies the concept of energy to electrical circuits. In particular, pupils learn that while current is not used up in the circuit, energy is. This work focuses on distinguishing between two abstract concepts: electricity as ‘flowing stuff’ and electrical energy as something that is identified by input and output effects. Its effects are associated with the brightness of bulbs and its origins in the voltage rating of batteries. There are necessary simplifications in the treatment, as appropriate to this early unit.

KS3 Physics: Where the unit fits in

This unit uses ideas developed in the key stage 2 programme of study. It builds on ideas introduced in unit 6G ‘Changing circuits’ and unit 4F ‘Circuits and conductors’ in the key stage 2 scheme of work.

This unit should precede unit 8J ‘Magnets and electromagnets’ and unit 9I ‘Energy and electricity’.

KS3 Physics: Expectations

At the end of this unit

in terms of scientific enquiry

most pupils will: select and use appropriate equipment to investigate circuits which include cells, bulbs and switches; measure current; identify patterns in their results and draw conclusions about series and parallel circuits; describe hazards associated with electricity and how to deal with them

some pupils will not have made so much progress and will: explore circuits using appropriate equipment; identify patterns in their results and use these to describe the behaviour of simple circuits; identify and report on hazards associated with electricity

some pupils will have progressed further and will: plan and carry out a systematic investigation of series and parallel circuits to obtain sufficient evidence to draw conclusions; give examples of the development of scientific ideas about electricity, eg Galvani and Volta on electric current, and explain how electricity can be hazardous to humans in terms of physical processes

most pupils will: construct a range of working electrical circuits and represent these in circuit diagrams; state that electric current is the same at all points in a series circuit and divides along the branches of a parallel circuit; use a flow model to describe resistance and to distinguish between electric current and energy transfer in a circuit; compare and contrast the advantages of series and parallel circuits in use, eg fuses, ring main

some pupils will not have made so much progress and will: construct simple electrical circuits and represent these diagrammatically; give examples of useful circuits; state safety rules for use of electricity

some pupils will have progressed further and will: relate voltage of cells and batteries qualitatively to energy transfer in circuits; use a flow model to explain the difference between electric current and energy transfer; apply the idea that nerves are electrical conductors to explain electrical hazards

KS3 Physics: Prior learning

It is helpful if pupils:

  recall that a complete circuit is required for electrical devices to work

  can connect a circuit

  can draw and interpret standard electrical symbols for connection, cell/battery, bulb and switch

KS3 Physics: Health and safety

Risk assessments are required for any hazardous activity. In this unit pupils:

  test fuses and use high currents (at low voltage)

  must not experiment with mains equipment

Model risk assessments used by most employers for normal science activities can be found in the publications listed in the Teacher’s guide. Teachers need to follow these as indicated in the guidance notes for the activities, and consider what modifications are needed for individual classroom situations.

KS3 Physics: Language for learning

Through the activities in this unit pupils will be able to understand, use and spell correctly words and phrases relating to:

  circuit components, eg battery, cell, bulb or lamp, connecting wire, switch, power supply, fuse

  electrical concepts, eg current, resistance, energy transfer

Through the activities pupils could:

  collaborate with others to share information and ideas, and solve problems

  identify the main points in each paragraph, distinguishing key points from supporting material

  follow the sequence of actions, processes or ideas being described

  use skimming, scanning, highlighting and note making as appropriate to different texts

KS3 Physics: Resources

Resources include:

  battery-powered appliances, eg torch, motorised toy

  variable resistors or potentiometers, eg dimmer controls

  low-voltage model ring main and/or series lighting array

  steel wool and fuse wire

  water flow model of electrical circuit or alternative model

  secondary sources about the work of Volta and Galvani and about the use of pacemakers and defibrillators

Out-of-school learning

Pupils could:

  talk to adults about the control and safe use of domestic mains appliances, including fuses (caution them not to experiment with mains equipment)

    KS3 Physics: How do electrical circuits work?

   to make and test predictions about circuits

   how to represent simple circuits using symbols

   that a cell/battery provides an electric current which travels round the circuit

   that a switch breaks the circuit and stops the electric current

   Use class discussion to review pupils’ knowledge and understanding of electrical circuits, eg draw a simple pictorial representation of a single cell and a single bulb (without holder) on the board. Ask individual pupils in turn to draw connections to make the bulb light. Discuss/vote on whether each one will work. Also ask if differently drawn circuits are the same. Repeat with more than one cell and bulb, in series. Alternatively, ask pupils to work in groups doing the same exercise using prepared cards.

   Ask pupils to test their predictions about whether the bulbs will light using short lengths of wire. Some pupils may need to be reminded about removing insulation from the wires. Others will need to identify the connection points on both the cell and the bulb. Pupils should record their observations, using conventional symbols. Pupils continue to explore the circuits by including simple switches.

   Ask pupils or groups of pupils to explain their observations to others.

  make and explain predictions about circuits, eg two connections are needed to light a bulb, there has to be a complete circuit, the battery provides ‘something’ to the circuit

  support their predictions by demonstration circuits, or circuit diagrams

  explain that the bulb(s) light because electricity travels round the circuit

   Encourage pupils to work systematically, laying out circuits in simple shapes and tracing continuity with their fingers.

   Pupils should be encouraged to use conventional symbols.

   Some pupils may think only one wire is active – unipolar model. Others may think that current flows out of both terminals of a battery and it meets with a ‘clash’ in the bulb, causing light – clashing-current model. Many think that current travels round a circuit from the battery, getting used up as it goes, so that there is less current at the ‘end’ of the circuit – current-consumed model. Fewer will hold the idea that current is unchanged – current-conserved model.

   to use ideas about complete circuits to describe how a switch works

   to devise a system for fault finding using knowledge of circuit ideas

   to test and evaluate their system

   to collaborate with others to share information and ideas, and to solve problems

   Demonstrate to the whole class how a torch works.

   Provide each group of pupils with a device or circuit that is not working and ask them to find the fault. Help them to devise a checking system to find faults, eg using ideas of circuit continuity or substitution of a component that they know works. Ask pupils to demonstrate their system to another group, and set a fault for that group to find.

  present an account in speech, diagrams or writing to explain the working of an appliance

  show their understanding of circuit ideas by successfully finding fault(s)

   This activity can be differentiated by the number and type of faults.

   Extension: pupils could be asked to explain how a similar appliance works.

   This work could be linked with unit 7D ‘Using control to control a display’ in the design and technology scheme of work.

    KS3 Physics: What happens in a circuit?

   that the nature and number of components in a circuit affects current flow

   to measure current with an ammeter

   that current in a series circuit is not used up by components

   to use the term resistance to mean opposition to flow of electricity

   Provide pupils, for work in small groups, with a battery and several identical bulbs. Ask them to explore connecting them in series, and to note patterns in their observations of the brightness of bulbs.

   Show pupils how to measure current in their circuits. Demonstrate how to connect an ammeter and how to use it carefully. Ask them to measure the current at one point in a circuit and predict the current at other places. Extend the work to include circuits with different numbers of cells.

   Draw on pupils’ experience of other electrical circuits, eg dimmer switches, and of other uses of the term ‘resistance’ to develop the qualitative idea of electrical resistance.

   Establish that the readings are constant for a given circuit, perhaps using a demonstration as a follow-up, as anomalous results can confuse pupils. Demonstrate with a variable resistor in circuit, eg dimmer switch.

  describe how increasing the number of bulbs reduces their brightness in a series circuit

  use an ammeter with care

  measure and record current in simple series circuits

  know that current does not change in a simple series circuit, that it is not ‘used up’ as it travels in the circuit

  use the term ‘resistance’ in describing circuit effects

   Check that the bulbs are matched to the voltage of the battery so that there is a change in brightness and bulbs do not ‘blow’.

   Digital ammeters are easier to read than those with analogue scales, though pupils may then find it harder to see approximately equivalent currents. Show pupils how to ensure an ammeter is not damaged in use.

   The quantitative relationship between current and resistance will be covered at key stage 4. It may be helpful to make qualitative connections with physical resistance to movement, such as friction.

   that cells and batteries are a source of electrical energy

   that a battery is a number of cells connected together with regard for polarity

   that a cell’s voltage has a chemical source

   Ask pupils the purpose of cells and batteries in a circuit. Provide cells and batteries marked with different voltages, eg 1.5, 4.5, 9V, and link their use with the concept of energy as ‘the ability to make things happen’, eg greater voltage rating, more bulbs light, so that voltage is understood simply as what makes the current flow.

   Raise the issue of polarity of cells and ask pupils to name a simple rule for connecting cells to make a battery, eg in a series positive connects to negative. Show the inside of a dry cell, identifying the connections to the positive and negative electrodes. Link the chemical origin of the cell’s voltage to pupils’ experience of ‘leaking’ and ‘dead’ batteries.

  identify a cell or battery as a source of energy

  describe why cells have positive and negative terminals, and connect them correctly in circuits

   At this stage it is sufficient for pupils to think of a battery as something that drives the current and provides the energy it carries.

   Pupils will use a voltmeter in unit 9I ‘Energy and electricity’. They will also investigate simple chemical cells.

    KS3 Physics: How can we explain what happens in electrical circuits?

   to distinguish between energy and electric current in a circuit

   to use a model to explain ideas about electric circuits

   Draw together the observations pupils have made about their circuits, eg current is not used up around the circuit, the cell which provides energy to the circuit runs down, energy is transferred from the cell to components in the circuit. Ask pupils to try to explain the difference between current and energy. Introduce the idea of a model, to show something has to be imagined such as the inside of circuit components, eg the water circuit can be used with a pump as cell, and water flow as electric current. Show how this demonstrates the concept of resistance of components in the circuit. Other models are possible, eg a bicycle chain, trucks carrying loads, tight string.

  distinguish between current and energy, eg current just circulates back to the battery, energy is used to light a bulb

  explain current in terms of a model

   The important distinction between the material (current) and non-material (energy) is difficult for pupils at this stage. Models have an important role in developing concepts. Pupils need to understand that a model helps them imagine what is happening and doesn’t represent physical reality.

   to construct parallel circuits

   to predict the current in branches of a parallel circuit

   to identify patterns in measurements

   to apply the water model or a similar model to parallel circuits

   to consider the limitations of a model

   Ask pupils to set up parallel arrangements of bulbs and use a model to explain why bulbs connected in parallel remain at the same brightness.

   Show circuit diagrams of simple parallel circuits with identical components in each branch. Ask them to predict current readings and to check this by measurement. Follow up with a demonstration to confirm that the sum of the current flowing in each branch is the same as that flowing in the main circuit. This offers more evidence of current conservation.

   Demonstrate a water circuit, or other model, to show the effect of resistance in parallel. Ask pupils to think of ways in which electricity is not like water, eg when the wire breaks it doesn’t run out. Invite pupils to think of other models, and to discuss their strengths and weaknesses.

  explain how connecting bulbs in parallel allows each to shine equally brightly

  predict and explain measurements of current in different parts of parallel circuits

  explain these observations using a model

  identify strengths and weaknesses of a model for electricity

   Many pupils will be surprised that both bulbs are of equal brightness when two in series are much dimmer. Distance from a battery is often seen as important and pupils might suggest that a bulb is dimmer because it is ‘further from the battery’. Circuit boards are useful for laying out parallel circuits clearly, but they often have additional resistance at connections in the circuit – so beware. Variations in apparently identical bulbs can lead to anomalous results. It may help to swap the bulbs round.

   The nature and behaviour of electrons and charge is not required until key
stage 4. A flow model is adequate to explain all the work covered in key
stage 3.

    KS3 Physics: What kinds of circuits are useful and what are the hazards?

   to compare and contrast series and parallel circuits

   to plan a circuit as a model of a domestic ring main

   Demonstrate extensive series and parallel circuits, eg some commercial Christmas tree light sets and a model ring main, to prompt discussion of the advantages of parallel connections. Ask pupils to make a plan of a circuit and draw up a component list, eg use a single low-voltage power supply to build a ring main to supply five rooms with electric lighting; switches should be used to control the circuits.

  use ideas about series and parallel circuits to help decide on a plan

  describe the advantages and disadvantages of different circuit connections

Safety  

the low-voltage unit may trip if the current is too high. This can provide a link to the next activity

   that electrical energy from the battery is transformed by a fuse to light and heat; this can cause it to melt

   to plan safe procedures, recognising hazards

   Show the pupils a circuit with three cells, ammeter and variable resistor in series with a short length of steel wool. Reduce the resistance and observe that as the current increases, the steel wool gets hot and then fuses (melts).

   Provide lengths of suitably current-rated fuse wire and ask pupils to plan and then test them to (planned) destruction using low-voltage power supplies and a bulb in a new circuit. Discuss the reasons for the use of fuses, including the resettable ones in modern fuse boxes and the cut-outs in laboratory power supplies.

  explain how a fuse protects a circuit

  work safely

  compare predictions with observations, eg current to ‘blow’ a fuse

   Resettable cut-outs are not fuses; they are coils which use magnetic effects to detect current flows, and are better described as circuit breakers.

Safety  

choose fuse wire that will blow at a current lower than the bulbs in the circuit

   about hazards of mains supply

   Remind pupils of work they will have done in key stage 2 on the hazards of mains electricity. Point out that the supply voltage (230V) is capable of delivering much more energy than the batteries and low-voltage supplies used in the laboratory.

  associate high voltage with electrical hazards

   Extension: using secondary sources of information, pupils could write a safety leaflet about mains supply, using the term ‘voltage’.

   that the nerves are electrical conductors

   how scientists’ ideas can be used

   to identify the main points in a text, distinguishing key points from supporting material

   to follow the sequence of actions, processes or ideas being described

   to use skimming, scanning, highlighting and note taking as appropriate to different texts

   Describe simply how the nerves carry messages around the body (acting as electrical circuits) and invite pupils to imagine what would be the effect of the body being subjected to input from external currents. Provide pupils with secondary sources of information. Remind them of how to use texts to identify key points and sequence ideas. Ask pupils to research a topic of choice, and present an account, eg

    Galvani’s discovery of the effect of electricity on frogs’ legs, Volta’s explanation of this and his construction of the first battery to demonstrate the effect

    – the use of defibrillators or pacemakers for keeping the heartbeat regular

    – the effects of electric fences on people and animals

  provide descriptions and/or explanations of the effects of electric current on the human body

  describe in a clear sequence the work of scientists in developing ideas and applications of electric current

   The historical material could be used to show the interplay between empirical questions, evidence and scientific explanation.

    KS3 Physics: Reviewing work

   to apply knowledge and understanding to a range of circuits

   Provide a range of circuit diagrams, showing series and parallel connections, switches and fuses. Give some current values and ask pupils to work out others.

  determine current values in given circuits

   A software simulation could be used for generating questions and reviewing with pupils how circuits work.

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 Doc Brown's Revision  KS3 Science KS3 PHYSICS Unit 7K Forces and their effects

KS3 Physics: About the unit

In this unit pupils:

  consolidate and build on their concept of force and its measurement

  identify the origin of friction, air resistance, upthrust and weight and describe situations in which these forces act

  distinguish between mass and weight

  use the concept of speed

  relate forces acting to changes in motion

  identify situations in which forces are balanced and unbalanced

In scientific enquiry pupils:

  consider why it is important to repeat measurements

  measure distance, time and force including weight

  construct and interpret line graphs and use them to make predictions

  investigate floating in water of varying salinity, ensuring relevant variables are controlled

  investigate friction between solids, ensuring relevant variables are controlled

KS3 Physics: Where the unit fits in

This unit uses ideas developed in the key stage 2 programme of study. It builds on ideas introduced in unit 4E ‘Friction’ and unit 6E ‘Forces in action’ in the key stage 2 scheme of work.

Together, this unit and unit 6E ‘Forces in action’ in the key stage 2 scheme of work can be used as bridging units.

This unit lays the foundation for unit 9J ‘Gravity and space’, unit 9K ‘Speeding up’ and unit 9L ‘Pressure and moments’. It also relates to unit 7D ‘Using control to control a display’, unit 8A(ii) ‘Exploring materials (resistant materials)’, and unit 9A(ii) ‘Selecting materials (resistant materials)’ in the design and technology scheme of work.

KS3 Physics: Expectations

At the end of this unit

in terms of scientific enquiry

most pupils will: make predictions about upthrust, test these and relate their findings to scientific knowledge; make suitably precise observations, including repeats to check reliability, and use these to plot graphs; investigate friction, identifying and controlling key factors

some pupils will not have made so much progress and will: make predictions about upthrust, test these and identify patterns in their results; with help plot graphs of their results; make relevant observations using appropriate equipment

some pupils will have progressed further and will: explain how they made a fair comparison in their investigation of friction; interpret their results on floating, using knowledge of balanced forces to explain conclusions; explain how the scales they chose and lines they drew on graphs enabled them to show data effectively

in terms of physical processes

most pupils will: identify directions in which forces act and describe situations in which forces are balanced; distinguish between mass and weight, giving examples; describe some ways of reducing friction and some situations in which friction is useful; describe what is meant by speed

some pupils will not have made so much progress and will: identify forces, eg friction, upthrust and weight; recognise that friction opposes motion, upthrust pushes upwards and weight pulls downwards; compare speeds qualitatively

some pupils will have progressed further and will: show how forces can combine to give a resultant effect which depends on both the sizes and directions of the forces; describe how weight is caused by gravity and how gravity is different on the Earth and on the Moon; explain contact friction in simple terms

KS3 Physics: Prior learning

It is helpful if pupils:

  know that pushes and pulls change the speed, direction or shape of an object

  know how to measure distance and how to use a forcemeter to measure force in newtons

  know that forces act in a particular direction and this can be indicated by arrows

  have experience of the effects of a variety of forces, eg magnetic, gravity, friction, air resistance

KS3 Physics: Health and safety

Risk assessments are required for any hazardous activity. In this unit pupils:

  use heavy weights

  stretch springs and rubber bands

Model risk assessments used by most employers for normal science activities can be found in the publications listed in the Teacher’s guide. Teachers need to follow these as indicated in the guidance notes for the activities, and consider what modifications are needed for individual classroom situations.

KS3 Physics: Language for learning

Through the activities in this unit pupils will be able to understand, use and spell correctly:

  words and phrases with different meanings in scientific and everyday contexts, eg drag, upthrust

  words with a more precise meaning in scientific contexts than in everyday contexts, eg weight, mass, density

  words and phrases relating to scientific enquiry, eg repeat reading, line of best fit

Through the activities pupils could:

  identify the main points of a talk, TV programme, etc

KS3 Physics: Resources

Resources include:

  immersion tank for objects to float and sink in

  scales marked in grams, kilograms and newtons, including personal scales

  lubricants, eg car oil, graphite

  videos/pictures of the effects of friction, and of a person floating in the Dead Sea or similar

  Highway Code (stopping distances)

KS3 Physics: Out-of-school learning

Pupils could:

  collect advertising and publicity material relating to streamlining and reducing friction, eg in cars, bicycles, sports clothing, oils and lubricants

  think about buoyancy and what helps them to float when swimming

  think about gravitational attraction when viewing films, videos and television programmes showing activities such as hang-gliding or skydiving

    KS3 Physics: Where do we come across forces?

   about a range of forces

   how to measure forces

   Review what pupils know about forces by presenting them with a number of quick activities, eg

    – weighing objects with a forcemeter

    – pushing an ice cube and a wooden block across a smooth surface

    tying or untying a knot in plastic and natural string

    – explaining how the time taken for a piece of paper to fall varies with the amount it is crumpled up

    – pulling strong magnets apart

    stretching a spring

    and questions, eg

    What force is acting here?

    What is its direction?

    Why are the forces changing?

   Discuss observations and answers with pupils.

  identify forces, eg magnetic attraction, friction

  use a forcemeter

  explain the observations they make, eg the plastic string is smoother so there is less friction and it is easier to untie

   This activity is intended to help teachers find out what pupils know and understand about forces from work in key stage 2. Teachers will need to take this into account in later work.

   Pupils are likely to have encountered a range of forces at key stage 2 and to have measured them using a forcemeter.

    KS3 Physics: Why do things float?

   that when objects are immersed in water there is an upthrust on them

   to draw conclusions from experimental results

   that when objects float the upthrust is equal to their weight

   that density is mass divided by volume

   Present pupils with floating objects which they can push down to feel the upthrust pushing up. Extend the range of objects and ask pupils to predict which will float, and to weigh them in air and immersed in water. Compile a table of results and ask pupils to identify patterns and draw conclusions from these. Ask pupils to record their results and explanations, eg by annotated drawings showing the forces acting on the objects. Discuss pupils’ ideas with them, referring to the work of Archimedes. Encourage generalisations, eg light for size, and show how to calculate density. Displacement of water can be used to measure volume (refer again to Archimedes).

  state that all the objects weigh less in water than in air

  explain their observations in terms of an upward force from the water ‘cancelling out’ some of the downward force of the weight

  recognise that objects which float show a zero weight reading

  state that an object will float in water if it is less dense than water

   Pupils may have met the term ‘density’ but will need help with calculations.

   Pupils will measure the density of objects using displacement in unit 8H ‘The rock cycle’.

   Archimedes checked the purity of a gold crown by measuring its volume by displacement.

    KS3 Physics: Why do things float? (Cont.)

   to choose which measurements and observations to make

   to compare results with those of others in order to evaluate their work

   that upthrust is different in different liquids

   Show pupils pictures either of people floating in the Dead Sea or of similar situations. Tell them of claims that it is easier to float in sea water than in fresh water. Ask them to suggest how they could test this. Remind them of the previous activity, provide them with samples of fresh water and sea water of varying salinity and ask them to investigate the claim and to produce a brief account using a combination of methods, eg drawings, tables, bullet points. Ask pupils to explain to others what they did, why they chose to do it that way, what conclusions they drew and to ask questions about other pupils’ methods. Draw together the outcomes and discuss the methods chosen, eg depth of immersion, number of measurements.

  make measurements which enable them to test the claim

  evaluate their methods

  state that some liquids produce a greater upthrust on an object than others

   As in the previous activity, teachers may wish to extend this work to a discussion of density.

   Pupils could be asked to find out about buoyancy aids and how these help them to float.

   that when an object is stationary the forces on it are balanced

   that the direction of a force can be represented by an arrow

   Remind pupils that when an object floats its weight is balanced by the upthrust. Ask them to suggest why we cannot float in air. Demonstrate a number of situations in which there are easily identifiable balanced forces on a stationary object, eg a tug of war, a paper clip or magnet held up by magnetic attraction or repulsion, a helium balloon floating at a fixed height, and ask pupils to identify the forces, and the directions in which they are acting. Extend to other contexts, eg a book resting on a table, an object suspended from a string. Test pupils’ understanding by showing them diagrams in which forces of given magnitude are represented by arrows and ask them questions, eg

    – Are the forces balanced?

    – Will it begin to move? In which direction?

    – What force would be needed to stop the object sinking?

    – Why can’t we float in air?

  identify the forces on an object and the direction in which they are acting

  demonstrate understanding that forces on a stationary object, eg upwards and downwards, are equal

   At this point balanced forces are considered in relation to stationary objects. The effect of balanced forces on a moving object will be covered in unit 9K ‘Speeding up’.

   A video can be used to show a range of balanced-force situations.

    KS3 Physics: How do different materials stretch?

   to draw an appropriate curve/line graph to fit quantitative data, including choosing the scales

   why it is important to repeat measurements

   to describe and compare trends shown in graphs

   to make predictions from a graph

   to use a graph to identify anomalous data

   Ask pupils about work they did on stretching materials in key stage 2. Establish that they understand that the greater the force pulling down on a material the more it stretches. Ask pupils to explore this in more detail by adding weights to a spring, measuring the extension and predicting the extension when additional weights are added. Help them to plot a suitable graph of their results.

   One way of supporting graph plotting is to get each pupil to stand in line at a height representing the value. Two other pupils, suitably marked, represent the axes, and lie on the ground and stand to the left. (For more details see Getting to grips with graphs (AKSIS, ASE, 1999).)

   Ask pupils to repeat the experiment with a rubber band and to plot a similar graph. Before they draw a curve through the points suggest they repeat their readings once or twice. Plot all readings and help pupils to decide what line to draw. Show examples of the graphs for both the spring and the rubber band. Ask pupils to describe the differences between them and to explain what they show about the differences in stretch.

  represent the collected data on an appropriate line graph

  explain how they decided on their line of best fit, using repeated measurements and identifying anomalous results

  describe and compare relationships shown by the graphs, eg with the spring, every time you add 0.1N it extends another 0.5cm, but with the rubber band the prediction is more difficult

   If some pupils need additional help with graph plotting, this could be done while others take repeated readings, which could then be treated as a class set.

   The force/extension graphs for rubber bands are nonlinear at the extremes.

   With some pupils it may be better to measure length, not extension, and to compare springs of different stiffness.

   Other pupils could be encouraged to relate the stretching of materials to the idea of forces between particles. Unit 7G ‘Particle model of solids, liquids and gases’ includes an introduction to particle theory (not including interparticle forces).

Safety

keep feet out of the way in case the elastic band breaks, eg by putting a large box or tin underneath so that feet are automatically clear

    KS3 Physics: Checking progress

   that there are many situations in which forces are balanced

   how to represent balanced forces with arrows

   Review the way the direction of a force can be represented by an arrow. Tell pupils they can also be scaled to show size. Give representations of the floating, sinking and stretching situations. Ask pupils to draw arrows to show that the forces are balanced. Discuss how the elastic force in a spring/rubber band increases to balance the increased weight of an object.

  identify the forces which are balanced in a range of situations

  use arrows to scale to show situations in which forces are balanced

   Interactive CD-ROMs could be useful for recapping this section and to introduce the next.

    KS3 Physics: What is weight?

   that mass is the amount of matter in an object and is measured in kilograms

   that weight is a force and is measured in newtons

   that weight is caused by gravity acting on a mass

   Ask pupils to ‘weigh’ objects using scales marked in both grams or kilograms and newtons. Use bathroom scales for pupils themselves if possible. Collect data and help pupils distinguish mass (in g/kg) as a measure of ‘stuff’ in an object and weight as a force measured in newtons.

   Alternatively provide a range of labelled masses and ask pupils to weigh them with forcemeters. Ask pupils to draw a graph of mass against weight and use this to work out the weight of other masses shown on their scale. Discuss these results and establish that the relationship shown is (approximately) 1 kilogram (1000 grams) mass has a weight of 10 newtons. Provide pupils with household items whose mass is marked and ask them to work out the weights.

  distinguish between mass and weight

  record measurements of mass and weight in appropriate units

  describe and use the relationship between mass and weight, eg on Earth a mass of 1kg has a weight of about 10N

   Pupils will have weighed objects in grams/kilograms and measured force in newtons at key stage 2.

   Some pupils may be sensitive about their weight (or mass).

   In unit 9J ‘Gravity and space’ pupils will study the importance of gravitational attraction in the solar system and its effect on the weight of objects on different planets.

   Extension: tell pupils that weight is caused by gravity, and that gravity on Earth is different to gravity on the Moon. Pupils could find out what effects gravity had on astronauts when they visited the Moon.

Safety  

take care when lifting heavy weights

    KS3 Physics: What does friction do?

   that friction is a force which opposes motion

   how friction between two surfaces can be reduced with a lubricant

   Remind pupils of the experiments they did at the beginning of the unit and ask them why the wooden block and ice cube or string and plastic thread behaved differently. Carry out some quick demonstrations, eg oiling a wheel, to illustrate the importance of lubricants, and ask pupils to explain how the lubricants work.

  explain differences in behaviour in terms of differences in frictional forces

  identify characteristics of lubricants, eg often liquid, smooth, and explain their action, eg smooth out rough surfaces

 

   about factors affecting frictional forces

   to investigate one variable while keeping others constant

   to represent quantitative data in a graph

   to make predictions from a graph

   Ask pupils to suggest what other factors might affect friction between an object, eg a wooden block or weighted margarine tub, and a surface. List the suggestions and tell pupils you are going to show them how to set up an investigation. Do so making deliberate mistakes, eg changing the surface area of the block when investigating the effect of weight; saying the same person must always measure the time taken to slide down a ramp. Ask pupils to point out any mistakes you make and to tell you what you should do.

   Help pupils to plan what to investigate and how to do it, ensuring that the plan will result in data that can be represented on a graph.

   Ask them to use their graphs to predict a value not measured and then test this value experimentally. Compile a class set of information about factors affecting friction.

  identify factors, eg weight, surface area, that might affect the frictional force between two surfaces

  identify and explain which variables need to be kept constant in order to obtain reliable data

  plot a suitable graph from their data and explain what it shows

  make and test a quantitative prediction from a graph

   Pupils are likely to have had many experiences of controlling variables in key stage 2, although they may not have used these terms. However, they may find it difficult to distinguish between quantities they need to keep constant and those that are not relevant.

   In key stage 2 pupils are likely to have investigated friction by dragging shoes or weighted containers across different surfaces. If so, they should be encouraged to investigate other factors, eg weight, surface area, effect of lubricant such as water.

   that frictional forces can be useful

   to identify the main points of a talk

   Present pupils with a set of cards with a series of statements, eg friction always slows things down, shoelaces stay tied because of friction, friction is useful to gymnasts, matches light because of friction, cars need friction to keep moving, and ask pupils to say if they are true/partly true/false. Discuss answers with the pupils and draw out the idea that friction is often helpful. Emphasise the importance of friction in walking and for wheeled vehicles, eg by showing a video clip of cars, people on ice or of vehicles stuck in sand. Show pupils pictures/examples of the treads on tyres and ask them to suggest how they work, or ask them to write a story of imagination, ‘A world without friction’. Ask pupils to produce an information card, eg ‘Ten things you never knew about friction’.

  describe examples where frictional forces are helpful

  explain why friction is important in the movement of vehicles

  present information about friction clearly and concisely

   The phrase ‘the real McCoy’ is thought to have originated from lubrication systems for locomotives, invented by the American Elijah McCoy, son of a runaway slave.

   Extension: pupils could be asked to find out about safety regulations for car tyres and why these are important.

    KS3 Physics: What affects how quickly a car stops?

   that stopping distances of vehicles relate to frictional forces and speed

   about speed and the units in which it is measured

   how to interpret distance/time graphs qualitatively

   Remind pupils of the importance of friction in driving cars forward and ask them to describe what happens when cars/bicycles try to stop suddenly on greasy/wet/smooth roads and which factors affect stopping distances.

   Show pupils the speed/stopping distance data in the Highway code and ask for interpretations. Some pupils could plot stopping distances against speed and be asked to describe the trend shown.

   Draw out pupils’ understanding of what speeds actually tell them. Explore pupils’ qualitative understanding of speed by posing questions, eg How would you find out who in the class runs fastest?

   Extend this by giving pupils distance/time graphs, eg of a journey to school partly on foot and partly on a bus, a journey home on a tricycle, a trip in a lift up a high building, and asking them to ‘tell the story’ of the journey. Discuss with pupils and tell them a story of a journey and ask them to turn it into a graph.

  identify that, for a given car, the stopping distance relates to its speed

  explain in words the units of speed, eg mph, km/h

  describe the journey shown in a speed/time graph, eg for the first ten minutes he didn’t go very far, about a quarter of a mile, but in the next ten minutes he went four miles, so he probably got a bus or a lift

   Speed may be the first derived unit pupils have encountered.

   The stopping distances in the Highway code are historical and are based on the performance of a Ford Anglia. Most modern cars are better than this, with sports cars typically having the shortest stopping distances and ‘people carriers’, among family cars, having the longest.

   A spreadsheet could be used to model stopping distances under different conditions.

    KS3 Physics: Reviewing work

   to recognise useful and unhelpful frictional forces

   to bring together ideas about forces and motion and to make links between them

   Present pupils with a context, eg a bicycle or a picture in which there is a variety of examples of friction. Ask them to identify these and explain which are useful and which are not.

   Draw together pupils’ knowledge of the key ideas in the unit by asking them to draw a concept map using appropriate terms, eg balanced, friction, upthrust, gravity, weight, mass, movement, speed. Discuss pupils’ maps with them. It may be helpful to agree a class summary map.

  identify, and draw representations to show, useful frictional forces, eg at brakes, and unhelpful frictional forces, eg at wheel axles

  make appropriate links and explain their reasons for them

   Extension: teachers may wish to extend this work with some pupils to the formal definition of speed. This is covered in unit 9K ‘Speeding up’. It is not necessary to distinguish between speed and velocity at this stage.

   Many pupils will be familiar with making concept maps from their work in primary science. (A concept map is used in unit 7E ‘Acids and alkalis’.)

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 Doc Brown's Revision  KS3 Science KS3 PHYSICS Unit 7L The solar system and beyond

KS3 Physics: About the unit

In this unit pupils:

  consolidate their ideas about the Sun and Moon, and use models of these to explain phenomena such as eclipses and the seasons

  learn that planets and satellites are seen by reflected light and that the Sun, as a star, emits light

  compare the Sun with other stars

In scientific enquiry pupils:

  consider how evidence about the solar system has been collected and interpreted

  use models to explain phenomena

  present data as a line graph and interpret this

  evaluate the strength of evidence obtained

  use data from secondary sources to answer questions about the solar system and the stars

KS3 Physics: Where the unit fits in

This unit uses ideas developed in the key stage 2 programme of study. It builds on ideas introduced in unit 5E ‘Earth, Sun and Moon’ and unit 6F ‘How we see things’ in the key stage 2 scheme of work.

The unit relates to unit 9J ‘Gravity and space’. Reflection of light is covered in unit 8K ‘Light’.

The historical impact of discoveries about the universe is covered in unit 21 ‘From Aristotle to the atom’ in the history scheme of work.

KS3 Physics: Expectations

At the end of this unit

in terms of scientific enquiry

most pupils will: describe and explain a phenomenon of the solar system, eg solar eclipse; describe ways in which evidence about the solar system has been collected; interpret patterns in data with respect to a model of the solar system, eg the tilt of the Earth causing seasonal variation; select information from secondary sources to present a report about a planet and evaluate the strength of evidence from data

some pupils will not have made so much progress and will: describe a phenomenon of the solar system using some scientific terms; describe patterns in seasonal variation, eg day length, climate; use simple secondary sources to collect information about a planet

some pupils will have progressed further and will: describe and explain a phenomenon of the solar system, showing that explanations have changed over time; use a model of the Earth, Moon, Sun system to explain patterns in data, eg seasonal variations, and relate this to real observations; use a range of secondary sources in finding information to report on aspects of the solar system

in terms of physical processes

most pupils will: relate eclipses, phases of the Moon and seasonal changes to a simple model of the Sun, Earth and Moon system; describe the relative positions of the planets and their conditions compared to Earth; state that the Sun is a star and that stars are light sources, while planets and other objects in the solar system reflect light

some pupils will not have made so much progress and will: describe how the Moon orbits the Earth and the Earth spins while orbiting the Sun; identify some differences between features of the Earth and other planets; recognise that the Sun and stars are light sources but the Moon reflects light

some pupils will have progressed further and will: explain, using models, patterns or associations in data about the Earth and other planets in the solar system, eg relationship between distance from Sun and orbital period; use large numbers appropriate to these; make comparisons between the Sun and other stars

KS3 Physics: Prior learning

It is helpful if pupils:

  know that the Sun, Earth and Moon are approximately spherical

  recall how the position of the Sun appears to change during the day and how shadows change as this happens

  recall how day and night are related to the spin of the Earth

  recall that the Earth orbits the Sun once each year, and that the Moon takes approximately 28 days to orbit the Earth

KS3 Physics: Health and safety

Risk assessments are required for any potentially hazardous activity. In this unit pupils:

  study the Sun

Model risk assessments used by most employers for normal science activities can be found in the publications listed in the Teacher’s guide. Teachers need to follow these as indicated in the guidance notes for the activities, and consider what modifications are needed for individual classroom situations.

KS3 Physics: Language for learning

Through the activities pupils will be able to understand, use and spell correctly:

  words relating to the solar system, eg planets, asteroid, satellite, orbit, eclipse

  words with similar but distinct meanings, eg orbit, rotate

Through the activities pupils could:

  introduce, develop and conclude pieces of writing appropriately

  identify the main points in each paragraph, distinguishing key points from supporting material

  use skimming, scanning, highlighting and note making as appropriate to different texts

KS3 Physics: Resources

Resources include:

  secondary sources, eg internet, CD-ROMs, photographs, video clips, reference books, showing the phases of the Moon, Earth from Moon, solar eclipses, discussing the possibility of life on other planets, the apparent movement of stars across the night sky

  secondary sources giving seasonal data, eg temperature, day length, rainfall, for a variety of places

  suitable materials for making models of the Earth, Moon and Sun system and of the solar system or a planetarium

  datalogger with light sensor and heat sensor

KS3 Physics: Out-of-school learning

Pupils could:

  read more about the planets in the solar system and space travel, including science fiction

  visit museums, planetarium or virtual observatory through the internet, eg www.jb.man.ac.uk/

  watch TV programmes and use the internet to find out about current exploration of the solar system

  make and keep records of nightly observations of the Moon and stars and find out about the constellations

  contact local astronomy societies

    KS3 Physics: What is the cause of a year, a month, a day?

   to explain phenomena such as day and night, and the apparent movement of the Sun

   to represent the system as a model and as a diagram

   Pose these questions about time so pupils can review their knowledge and understanding of the relationship between Sun, Earth and Moon. Ask them to represent the system as a model made up from, eg a light source, football and tennis ball, and to use the model to explain the phenomena. Ensure that they can correctly identify the Sun, Earth and Moon in this model. Show pupils photographs, video clips, CD-ROMs and simulations to reinforce their knowledge.

   Challenge pupils to answer questions, eg

     Which way is ‘down’ in Australia?

     How do we know the Earth is a sphere and not flat?

     Why are there time zones?

  represent the Sun, Earth and Moon by spheres and identify them in a model or diagram representing the system

  use the model to explain how day and night occur, involving the Earth’s rotation

  use the model to explain the passing of a month and of a year

  use the model to explain why the Sun appears to move across the sky during a day

   At key stage 2 pupils will have considered evidence for the Sun, Earth and Moon being spherical and used models showing their relative positions and sizes.

   Extension: pupils could find out about the work of Harrison in developing a chronometer accurate enough to determine longitude precisely.

    KS3 Physics: How do we see the Sun and Moon?

   that there are luminous and non-luminous objects

   that the Sun is a light source, but the Moon and Earth are seen by reflected light

   Ask pupils to recall the difference between light sources and reflective surfaces. Discuss evidence that the Sun emits light (as a star) and that the Moon does not. Ask them whether or not the Moon and the Earth are light sources like the Sun. Discuss their evidence.

  distinguish between luminous and non-luminous objects

   Some pupils think that very reflective surfaces are sources of light.

Safety

– warn against looking directly at the Sun

   how the view from the Earth of the Moon causes the phases in a regular sequence

   to use information from secondary sources

   Provide pupils with images showing how the Moon changes shape over a 28-day period. Ask them to sequence these and help them to explain this in terms of the Sun as a light source. Encourage pupils to use models and images to improve their explanation, eg half-black polystyrene sphere on a stick moved around at head height.

   Show an image of the Earth taken from the Moon. Ask pupils if a Moon dweller would see the apparent ‘phases of the Earth’.

  sequence the phases of the Moon over a 28-day period

  explain how the view from the Earth of the Moon causes the phases in a regular sequence

   Newspaper reports of the phases of the Moon, sunrise and sunset times could be used in this work.

   Use other secondary sources, eg video clips and animations from CD-ROMs, to help develop mental links between models, diagrams and perception.

   Extension: pupils could make observations of the Moon at night and during the day, and record its changing phase and position in the sky.

    KS3 Physics: How do we see the Sun and Moon? (Cont.)

   how eclipses of the Sun occur

   how eclipses of the Moon occur

   about the evidence eclipses provide about the solar system and how scientists use it

   Remind pupils of the solar eclipse of 1999. Ask them to explain what caused this using diagrams and models, eg involving a light source, football, tennis ball, and ICT simulations. Challenge pupils to think about this, and to suggest answers. Clarify the importance of the slight angle of the Moon’s orbit relative to that of the Earth, and use this to explain the rarity of total eclipses. Help pupils to adapt their own diagrams of these phenomena to the scientific model.

   Extend to lunar eclipses. Provide pupils with an explanation of what these involve. Ask them to use their models to represent the process.

   Review this work by providing a set of diagrams showing stages of an eclipse, and ask pupils to put them in the correct sequence.

   Ask pupils to find out about some of the research projects based around the 1999 (or other) solar eclipse.

  sequence a series of images showing stages of an eclipse

  explain, using a model and diagrams, how eclipses of the Sun and Moon occur

  describe the evidence eclipses provide about the solar system, eg relative sizes and distances of the Moon and the Sun, and other phenomena, eg roosting of birds

   Many pupils will have been aware of the widely publicised solar eclipse in 1999. Internet sites and CD-ROMs are available which provide animated sequences explaining eclipses. Pupils sometimes confuse the phases of the Moon with an eclipse of the Moon.

   There are websites which operate as projects, so pupils can ‘tune in’ to scientists at work, eg the eclipse lab on the Science Museum website: www.nmsi.ac.uk/eclipse/eclipselab/

   to write about a physical phenomenon from a personal point of view

   to develop ideas into continuous text

   Use a video to show a solar eclipse and ask pupils to write about what it would be like to experience this event, describing the stages of the eclipse with accompanying pictures, eg in the style of a news report. Alternatively, ask pupils to find out or imagine how people in the past have interpreted the events of an eclipse.

  describe the experience of a solar eclipse

 

    KS3 Physics: What causes the seasons on Earth?

   to use a model to show that the axis of spin of the Earth is at an angle to its orbit round the Sun

   Ask pupils about any work carried out at key stage 2 on seasonal variation, eg changing hours of daylight throughout the year. Ask them for an explanation of this. Help pupils model the idea of the tilt of the Earth. Ask pupils to suggest ways in which the seasons differ from each other, eg position of Sun in the sky, climate.

  describe that the axis of spin of the Earth is at an angle to the Sun

  identify on a diagram or model parts of the Earth which are experiencing different seasons, due to their relative position to the Sun

   Work relating to the Earth’s orbit will have been done in key stage 2. However, pupils will not have related this to the seasons. This provides the opportunity to refine their use of the Sun, Earth and Moon model. Many pupils experience difficulty in thinking about the Earth’s spin and its orbit round the Sun at the same time. The use of video animation may help.

   to collect data about temperature and day length, using ICT

   to interpret first-hand and secondary data about temperature and day length

   to follow the sequence of actions and processes being developed

   Help pupils to use a datalogger to test the validity of the ‘tilted Earth’ explanation of the seasons, eg by placing a tilted globe at a distance from a source of light/ heat and using a heat sensor to monitor the change in temperature as it is moved from the north to the south pole along a line of longitude. Record and display the data as a graph for analysis and interpretation by pupils.

   Position the globe with Britain in a summer position relative to the light-source ‘Sun’. Place a light sensor on one point and slowly rotate the globe. Collect data illustrating the differing hours of day length in summer and winter positions, and how this is dependent on the orientation of part of the globe to the ‘Sun’.

   Provide pupils with secondary data about seasonal changes, eg temperature, day length. Ask pupils to use both sources of data to relate seasonal changes to the model of the Sun, Earth and Moon system that they have developed.

  interpret graphical data produced by a datalogger and relate this to knowledge about variations in day length and climate in different seasons

   An alternative arrangement is to use two or three trays of sand exposed to the same light source, but inclined at different angles and to record temperature changes.

    KS3 Physics: Checking progress

   to relate ideas about the Sun, Earth and Moon to familiar phenomena

   to introduce, develop and conclude pieces of writing appropriately

   to group sentences into paragraphs

   to develop ideas into continuous text

   Ask pupils to imagine that they are visitors to Earth from a planet in another part of the universe, which orbits and spins more slowly. How would their world be different from Earth? Ask them to write a scientific report to their home planet describing some of the new phenomena observed on their mission, eg day length, year length, seasons, phases of the Moon and eclipses.

   This could be extended by telling pupils that this other planet is not tilted and that its moon is much further from the planet. Help pupils to model the system and extend their account to seasons, eclipse and phases of the Moon.

  describe how differences in orbit and rotation time affect phenomena, eg day length, year length

  write an organised, continuous explanatory text of about 250 words

 

KS3 Physics: What does the solar system consist of?

   that our solar system includes the Sun, its planets and asteroids and the natural satellites of the planets

   that the planets orbit the Sun in similar ways to the Earth

   how evidence about the solar system has been collected and interpreted

   to use secondary sources to find out about planets

   to speculate on the possible conditions on other planets

   to identify the main points in each paragraph, distinguishing key points from supporting material

   to use skimming, scanning, highlighting and note making as appropriate to different texts

   Elicit pupils’ knowledge and understanding of the solar system. Ask them to name the planets they know and the order in which they occur from the Sun. Pupils could devise a mnemonic to memorise the planets in order. Brainstorm other information about the planets. Ask them to label the planets on a diagram, which includes the asteroids and natural satellites of the planets. Ask them what they think these other bodies might be made of.

   Discuss how astronomers obtain evidence of planets and other bodies in the solar system by use of telescopes and probes. Raise the importance of the size and positioning of the instrument, eg William Herschel, who discovered Uranus, built the largest mirror of his time in his kitchen. Ask pupils to use secondary sources to find out about the discoveries of William and his sister Caroline, and how they changed ideas about the solar system and the universe.

   Ask pupils what they think it would be like on other planets. Encourage them to think about how it would be different from Earth, eg surface, temperature, atmosphere, day length, year length. Ask pupils to search secondary data sources on the planets, eg books, internet and CD-ROMs, and, eg write a travel brochure for future visitors to the chosen planet, identify 10 things you want to know about a planet and find the answers.

  label a diagram showing the Sun, planets and asteroid belt and the natural satellites of the planets of the solar system

  explain that the planets orbit the Sun in similar ways to the Earth, but that their orbits take different times to complete

  describe how information on the planets in our solar system is obtained and used

  present relevant information about a planet in the solar system in an appropriate form, eg for a future visitor

  read information text with understanding

  use appropriate reading strategies to find information

   A visit to a planetarium could be used to support this initial activity on the solar system. The information gathered in this activity should be used as a stimulus for the next activity.

   A video, CD-ROM or internet site could provide an introduction to this section, eg www.nasa.gov/

   Pupils should be encouraged to write their report using ICT and to include images within it.

KS3 Physics: What does the solar system consist of? (Cont.)

   how to find out about the relative sizes of the Sun, Earth, Moon and other planets and the relative distances of the planets from the Sun

   to frame a question that can be investigated

   to search for patterns from ICT data

   to draw conclusions from data, evaluating the strength of the evidence

   Present pupils with information about the planets in the solar system, in the form of a spreadsheet. Show pupils how to sort the information, eg mass, diameter, distance from Sun, number of moons, length of year, length of planetary day, on the spreadsheet and how to use the applications to sort data and draw graphs. Ask them to draw conclusions from their graphs and explain to other pupils how strong they think the evidence is for these conclusions.

  frame a relevant question about which data from secondary sources can be collected

  present data on comparisons between characteristics of planets in a suitable way, eg table, chart or graph

  present evidence of relationships in data on aspects of planets

   To help pupils analyse the data, pre-prepare the spreadsheet in advance or allow pupils to enter data which they have collected about a planet.

   Care is needed in choosing scales. Models showing relative diameters and distances are usually made separately, because of scaling problems.

   Extension: pupils could use these applications to search for patterns within the planetary information, using the graphing function, eg Is distance from the Sun related to planetary year length? To mass? Is mass related to diameter? Other pupils could use the data to make scale models or drawings.

   that within our solar system only Earth is known to support any life forms

   to evaluate the strength of the evidence

   Ask pupils to consider the evidence collected about the solar system in the previous activities and to use it to support a discussion about the possibility of life existing on other planets. If necessary prompt with questions, eg

    What conditions are necessary for life forms to survive?

    Do any planets have these conditions?

    What evidence would we look for in searching for life?

    What is so special about Earth that it supports life?

   Help pupils to record the main points from the discussion and to evaluate how good their evidence is.

  state that within our solar system only Earth is known to support any life forms

  describe the conditions necessary for life in the solar system

  describe how strongly their evidence supports or does not support the idea of life elsewhere in the solar system

   Pupils could visit a website of an organisation that is searching for extraterrestrial intelligence, eg SETI, which includes an interactive game (www.seti.org/game/)

   In unit 7C ‘Environment and feeding relationships’ pupils consider how organisms are adapted to their environment.

   Work carried out in this section could form the basis of a classroom display or presentation.

    KS3 Physics: What is beyond the solar system?

   that the Sun and other stars are light sources

   that the apparent movement of the stars is a result of the Earth’s rotation

   that stars are spread throughout the universe

   Remind pupils of earlier work on the Sun as a light source and ask questions to elicit pupils’ knowledge about stars. Ensure that they understand how stars are different from planets, and that the Sun is a star.

   Invite pupils to think of questions to answer about the stars, eg

    Where are the stars?

    Why do we only see other stars at night?

    How did sailors and desert travellers use stars to navigate?

   Present evidence, eg from time-lapse photography images, to show how the stars appear to move across the night sky. Remind pupils of work carried out at key stage 2 concerning the apparent movement of the Sun in the sky, and help them to use this idea to explain the apparent movement of stars. Relate the movement of the Earth round the Sun to the changes in visible stars during the year, eg with a model planetarium.

  explain that we can see the Sun and other stars because they are light sources

  explain that we only see the stars at night because the Sun is much nearer to us and appears brighter

  use the idea of the Earth’s rotation to explain the apparent movement of the stars in the night sky

   Extension: pupils could be asked to find out about early ideas about what we can see in the sky and how constellations got their names.

   Unit 9J ‘Gravity and space’ extends the work in this section.

   KS3 Physics: Reviewing work

   to identify key ideas about the solar system

   Ask pupils to make up questions on topics of this unit for a quiz. They could be presented in various ways, eg as bingo or in the style of a TV quiz show, and played according to the agreed rules.

  produce relevant questions and correct answers to them

   If a classroom display or presentation has been made, this could be used in the review.

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 Doc Brown's Revision  KS3 Science KS3 PHYSICS Unit 8I Heating and cooling

KS3 Physics: About the unit

In this unit pupils:

  recognise the need for a temperature scale

  learn to distinguish between heat (as energy) and temperature

  learn about mechanisms of heat transfer: conduction, convection and radiation, and apply this to familiar contexts

  learn about expansion and change of state in solids, liquids and gases

  use the particle model to explain conduction, convection and change of state

In scientific enquiry pupils:

  draw and interpret line graphs from data collected

  carry out a survey of people’s perceptions of common temperatures

  investigate the effectiveness of different forms of insulation, controlling relevant variables

Note on the teaching of energy

This unit considers the idea that energy transfer results from a difference in temperature. This is an important concept, as most changes are a result of differences and energy changes are associated with them, eg a raised object falls, transforming its potential energy to kinetic energy. The unit also helps pupils distinguish heat (energy) from temperature. There has been much debate about the use of the word ‘heat’ for energy. The risk is that it might support the idea of a separate kind of stuff – as was current in science before the work of James Joule in the nineteenth century. It is used here in contexts which should avoid that misconception. The unit applies ideas of moving particles to explain the transfer of heat (energy) by conduction and convection, thus clarifying that, in this context, heat is a kind of movement. Particle models are also used to explain how matter changes state when energy is added or removed, so this unit needs to follow unit 7G ‘Particle model of solids, liquids and gases’ and unit 7H ‘Solutions’.

KS3 Physics: Where the unit fits in

This unit uses ideas developed in the key stage 2 programme of study. It builds on ideas introduced in unit 4C ‘Keeping warm’ and unit 5D ‘Changing state’ in the key stage 2 scheme of work.

In unit 7I ‘Energy resources’, pupils will have identified that when fuels burn they release energy and have noted the consequent rise in temperature.

In unit 7G ‘Particle model of solids, liquids and gases’, pupils will have encountered the particle model of matter.

In unit 9I ‘Energy and electricity’, pupils will study energy transformation and energy conservation.

Expectations

At the end of this unit

in terms of scientific enquiry

most pupils will: plan a survey of perceptions of temperature, using an appropriate sample; plan an investigation into methods of reducing heat loss; carry this out using ICT for recording temperature data and relate findings to practical implications; select effectively information from secondary sources to compare methods of preventing heat loss in houses; collect and interpret temperature data from a substance changing state

some pupils will not have made so much progress and will: use thermometers safely; present survey data using a chart or table; identify and control key variables in an investigation of insulators for reducing heat loss and draw practical conclusions; select information to report on ways of reducing heat loss in houses; draw a graph of temperature changes when a substance changes state

some pupils will have progressed further and will: make systematic measurements of temperature changes with a precision which enables reliable conclusions to be drawn in an investigation of insulators; evaluate different sources of information on domestic heat loss prevention methods; extrapolate from temperature data on change of state in terms of physical processes

most pupils will: give examples of common temperatures on the Celsius scale; distinguish between heat and temperature, describe energy flow as the result of temperature difference; describe some uses of good conductors and insulators and examples of conduction in solids and convection in liquids and gases; explain conduction and convection, expansion and change of state in terms of the particle model

some pupils will not have made so much progress and will: give examples of some common temperatures; describe some uses of good conductors and insulators; describe how insulators can reduce heat loss; describe how substances expand and change state

some pupils will have progressed further and will: give examples of a wide range of temperatures on the Celsius scale; compare conductivity of materials and relate this to their uses; use the particle model to explain change of state relating this to the forces between particles

KS3 Physics: Prior learning

It is helpful if pupils:

  know that temperature is a measure of how hot an object is

  can use a thermometer

  know that metals are good thermal and electrical conductors

  recall that evaporation occurs at the surface of a liquid

  know about the particle model of matter

  can describe differences between solids, liquids and gases

KS3 Physics: Health and safety

Risk assessments are required for any hazardous activity.  In this unit pupils:

  use hot water and electrical heaters

  observe heated metals, liquids and air

  use flammable and oxidising materials

Model risk assessments used by most employers for normal science activities can be found in the publications listed in the Teacher’s guide. Teachers need to follow these as indicated in the guidance notes for the activities, and consider what modifications are needed for classroom situations.

KS3 Physics: Language for learning

Through the activities in this unit pupils will be able to understand, use and spell correctly words:

  relating to heat transfer, eg conduction, convection, radiation, insulator, conductor

  with similar but distinct meanings, eg heat (as energy), temperature

  relating to scientific enquiry, eg sample size, trial measurements, evaluation, prediction

Through the activities pupils could:

  organise information in an appropriate sequence

  show relationships between ideas in writing by using link words, eg so that, and reservation words, eg although, if

KS3 Physics: Resources

Resources include:

  a range of thermometers

  temperature sensors and dataloggers

  range of insulating materials, eg felt, expanded polystyrene, duvet filling, cork, thermal lining for curtains

  ‘energy houses’ – lidded boxes which can be insulated using a variety of materials of varying thicknesses, using Velcro pads

  information on insulation in the home

  vacuum pump

  radiant heater

  ‘ball and ring’ or other expansion demonstration apparatus

  salol (phenyl salicylate)

Out-of-school learning

Pupils could:

  consider why different clothes are worn at different times

  think about how to keep food and drink warm or cool

     KS3 Physics: What’s the temperature?

 

 

   that temperature is a measure of how hot things are

   that the Celsius scale of temperature is used in science

   the values of the boiling point and freezing point of water on the Celsius scale and of some typical temperatures

   how to plan a survey, considering the importance of sample size

   Use two introductory activities to help pupils recall previous measuring experience and to raise the issue of scales.

   Two pupils put their hands in water, one in cold and the other in warm, then both simultaneously put their hands in lukewarm water and report how it feels; one claims it’s warm, the other that it’s cold. Ask them to check the temperature with a thermometer.

   Ask pupils to suggest values for common temperatures, eg freezing water, boiling water, room temperature, outside temperatures during different seasons, body temperature, the coldest place on Earth, the hottest place on Earth, hot oven temperature, safe (hygienic) fridge and freezer temperature. Then pupils:

measure or otherwise find out about these temperatures and produce a chart of temperatures such as a ‘temperature line’ or bar chart; or

– conduct a survey of perception of temperature values with adults or other class groups, and work out how much those surveyed estimate values too high or too low

  explain why using their senses is not a reliable way to measure temperature

  understand the need for a scale of temperature and use the Celsius scale of temperature

  combine results to produce a larger sample size

  present information in chart form so that it is easily assimilated

   A temperature line is an example of a number line, and should include negative values.

   Pupils could find out about these temperature values for homework.

Safety  

water must not be too hot

   that there are different kinds of thermometer

   Demonstrate or arrange for groups to use different thermometers to measure a range of temperatures.

  select an appropriate thermometer for a set of measurements

   Possible examples include sensors with dataloggers, digital display, bimetal strip, thermocouple, as well as liquid-in-glass.

     KS3 Physics: How do things get hotter or colder?

   to recognise heat as energy

   to use a model which associates energy flow with temperature change

   to make predictions and compare these with observations

   that heat flows as a result of temperature differences

   Remind pupils of year 7 work on the heating effect of burning fuels, where energy was released to cause temperature rise. Discuss the energy flow associated with the cooling of boiling water and the warming of ice in the classroom.

   Elicit pupils’ ideas about how heat and temperature are linked and establish that they are not the same thing. Ask pupils to predict and observe how the temperatures change when they, eg mix volumes of hot and cold water, boil different quantities of water with the same heater.

   Through questioning, help pupils explain why their predictions matched or did not match the observations they made.

  describe the flow of heat (energy) in an everyday situation of temperature change, eg the cooling of hot food

  relate a flow of heat to change in temperature

  relate a difference in temperature to a flow of heat

  give reasons for their predictions and for any differences between the predictions and observations

   Pupils often confuse heat and temperature. The distinction required is that heat is a quantity of energy and that temperature is the response of a material to the input of energy. Heat capacity can be left to key stage 4. The principle of energy conservation is covered in unit 9I ‘Energy and electricity’.

   Pupils should understand that heat naturally flows from a higher to a lower temperature. The fridge needs a power supply to make heat go the opposite way (details of its mechanism are not required here).

Safety  

care is needed with hot and boiling water

   that heat energy will flow more easily through good thermal conductors and less well through poor conductors

   Ask pupils to touch a number of materials, eg wool, metal, polystyrene, rubber, wood, glass, etc, and decide which feels coldest/warmest. Summarise opinions. Point out that all materials are at the same temperature – room temperature. Explain that the sensation of coldness is caused by the best conductors of heat conducting their body heat away most quickly. The temperature difference causing this flow of energy is between the pupils themselves and the object they touched. Remind pupils that we have a near-constant body temperature of about 37°C. Ask how this compares with the objects touched.

  explain that whether things feel warm or cold to the touch will depend on their conductivity as well as their temperature

   Pupils may have investigated thermal insulators for keeping things warm or cool at key stage 2. Some may think that thick clothes ‘make them warm’, as if the material is active rather than preventing the loss of heat generated by the body.

   Pupils should be dissuaded from talking about ‘the cold getting in’ when discussing the purpose of insulation.

     KS3 Physics: How do things get hotter or colder? (Cont.)

   that most metals are good thermal conductors

   that poor thermal conductors are called insulators

   how to use ICT to monitor temperatures

   Ask pupils to work in pairs to suggest why certain materials are used in cooking utensils, eg a wooden spoon (or saucepan handle) and a metal saucepan base. Demonstrate the difference in rate of conduction of heat,
eg using temperature probes and dataloggers to determine temperature of the tip of a rod and monitor the rate of temperature rise; temperature probes along length of rod. Use the demonstration to classify materials as good or poor thermal conductors.

  classify materials as conductors or insulators of heat

  interpret temperature data from datalogger

   Pupils find out about the properties of elements in unit 8E ‘Atoms and elements’ and more about metals in unit 9E ‘Reactions of metals and metal compounds’.

   Extension: compare the conductivity of a range of metals, eg aluminium, copper, steel, and relate this to claims made for different metal cooking utensils.

Safety  

take care to leave time for rods to cool before handling

   that liquids and gases are poor thermal conductors

   Demonstrate poor conductivity of water by trapping an ice cube at the bottom of a tube of boiling water using a small piece of gauze. Heat the top of the water to boiling point and show that the ice remains unmelted at the bottom. Temperature sensors linked to a computer could monitor different positions in the tube.

   Show highly effective insulating materials, eg expanded polystyrene, filling for duvets, and demonstrate that they are mostly trapped air, eg evacuate a sample with a vacuum pump.

  describe evidence that gases and liquids are poor conductors of heat

   This arrangement prevents transmission of heat by convection, which is covered in the next section.

   There is no transfer by convection in these materials because the air is trapped in small pockets.

   that evidence of conduction in solids, liquids and gases can be explained using the particle model

   Recall with pupils the idea that solids are made of particles called atoms and molecules. Introduce the idea that when energy as heat is absorbed by a solid, the particles move around their position in the solid more. This movement can be passed on to adjacent particles. Get pupils to enact this model of conduction: ask them to link arms firmly in a line (simulates a solid), then one pupil provides energy (‘heats the line’) by gently pushing and pulling the end of the line. The energy (movement) is conducted along the line. This happens less well if they are merely holding hands (liquid) and not at all if they are not linked (gas).

  simulate the conduction of thermal energy through a solid, liquid or gas

  apply the particle model to explain why metals are good conductors and why fluids are poor conductors of heat

   This is the first of three uses of the particle model (kinetic theory) in this unit. It builds on the introduction of particles in unit 7G ‘Particle model of solids, liquids and gases’ and unit 7H ‘Solutions’.

   The use of the particle model in explaining chemical reactions is covered in unit 8E ‘Atoms and elements’ and unit 8F ‘Compounds and mixtures’.

     KS3 Physics: How do materials change when they are heated and cooled?

   that movement of particles in solids, liquids and gases increases with increasing temperature and the particles move further apart

   to use the particle model to make predictions and to compare these with observations

   that expansion of a material will reduce its density

   Remind pupils of the different ways in which particles are arranged in solids, liquids and gases.

   Carry out a quick demonstration of expansion of a solid on heating, eg ‘ball and ring’, or by heating a horizontal metal rod clamped at one end, with the other end free to roll over a pin with a small paper flag attached. Discuss with pupils and get them to model, in terms of particles, why the rod/solid expands and contracts. Ask them to use the particle model to predict what would happen if a liquid or gas were heated or cooled, and check the prediction by demonstration or pupil practical work, eg

    – warm in a water bath a boiling tube filled with oil, with a bung placed in the top, into which has been placed a narrow vertical glass tube with the oil level part way up

    – warm with hands a large round flask containing water with a bung in the top, into which a narrow vertical glass tube has been inserted; either insert a small bead of oil in the glass tube, or invert the open tube into the water and watch the air bubble out

   Ask pupils to use the observations to explain why it would be dangerous to heat a completely sealed container of a liquid or gas.

  describe the expansion of all three states of matter on heating (in terms of particles moving more and taking up more space) and contraction on cooling (in terms of particles slowing down and taking up less space)

  relate different states to the different motion and arrangement of particles

   It is important to encourage pupils to apply the particle model themselves.

   A very common misconception is that particles themselves expand on heating. It is not obvious from the experimental results that this is incorrect and pupils will need to be given the scientific explanation, ie in terms of increasing separation of particles.

Safety  

ensure that containers of liq­uid and gas allow for expansion and can be heated safely

   that hot fluids rise due to expansion and cooler ones sink to take their place

   that expansion of fluids causes a change in density

   Review pupils’ ideas of upthrust and density by showing a helium balloon rise or by using similar stimulus material.

   Build a (tethered) hot-air balloon using ‘night lights’ as the source of hot air, or build a windmill suspended from a thread to be driven by the hot air rising from a 100W light bulb. Establish that these work because heated air moves upwards since it is less dense than cooler air, and point out that the air will come down as it cools.

   Use forceps to drop a crystal of potassium manganate (VII) down a glass tube into water, which is then warmed over a Bunsen burner, and observe the trail of purple water formed due to the convection current. Alternatively, place a bottle containing cold, colourless water on top of a bottle containing hot coloured water, so that the contents can mix. Repeat with the bottle containing the cold colourless water on the bottom.

  recognise common hazards and work safely with flames and hot light bulbs

  choose apparatus to undertake a successful design-and-build exercise

  describe how air or water moves when part is heated or cooled

   Upthrust and density are covered in unit 7K ‘Forces and their effects’.

   Beware of the incorrect statement ‘heat rises’. This is often used instead of ‘hot air rises’.

   Better results are obtained if the crystal is dropped down a narrow glass tube to prevent colouring the water from the top.

Safety  

flammable materials; potassi­um manganate (VII) is a harmful oxidiser (handle with forceps)

   how to organise information about a scientific topic into a coherent sequence

   Offer pupils a mixed-up written explanation of what they have just seen, including reference to energy transfer, and ask them to sequence it chronologically to describe convection currents.

  produce coherent text explaining how a convection current transfers heat

 

KS3 Physics: How do materials change when they are heated and cooled? (Cont.)

   to apply the particle model to explain convection in fluids

   Remind pupils that in a solid the particles are closely packed, while in fluids they can move past each other. Encourage them to speculate how the absorption of heat by fluids will cause movement of these particles.

   Present a model in which some pupils acquire energy, eg coloured paper resembling banknotes, from the source at the front of the room. Explain that those with the most money move fastest, but when they meet the others they give money away. So pupils move from the source towards the back of the classroom (top of the container) distributing money/energy on the way. Others take their place to be provided with energy until they are all warm.

  work with others to simulate convection, eg describe their role as a particle gaining and losing energy

   This is a complex model, which uses several elements of the kinetic theory; for some pupils a description of an example of convection would be more appropriate.

   that radiation energy (infrared) can travel through a vacuum

   Conduction and convection both need particles to carry energy when heat is transferred. Ask pupils if heat can travel through nothing at all (a vacuum).

   Draw connections between the behaviour of heat and light from the Sun,
eg both radiate from the source. Demonstrate focusing (use of burning glass) and reflection of infrared radiation using radiant heaters or hot light bulbs.

  distinguish between transfer of thermal energy via conduction and convection and transfer by radiation, with reference to requirement for a medium

   Make the distinction from sound, which does need a medium to travel. Beware of pupils confusing thermal radiation with radioactivity (often called radiation).

Safety  

beware of trailing leads if us­ing mains equipment. Ensure that pupils cannot touch heating elements

    KS3 Physics: How can we reduce energy waste?

   that insulation can reduce unwanted energy transfer

   Review pupils’ key stage 2 work on insulators, where they may have investigated keeping cups of liquid warm or preventing ice cubes melting.

   Recap year 7 work on the need to conserve energy resources. Ask groups to discuss the ways used to prevent energy escaping from homes, eg loft insulation, heavy curtains, cavity-wall insulation.

   Use models to explain how these methods work, eg double glazing, draught excluders.

  describe and explain how a house can be fitted out to reduce heat loss

 

    KS3 Physics: How can we reduce energy waste? (Cont.)

   to frame a question that can be investigated

   to use preliminary work to decide what to measure and the range of measurements to be made

   to decide whether it is appropriate to use ICT for collecting data

   to decide how best to present the data and to draw conclusions from this

   to evaluate their conclusions

   Ask pupils to devise a way to compare the effectiveness of different insulation techniques, using a small lamp as a heating source in an ‘energy house’, eg use dataloggers to produce on-screen graphs of heating or cooling. Help pupils to decide what factors to consider, eg the starting temperature of the house and thickness, nature and positioning of insulation material.

   Encourage pupils to make some trial measurements and to consider how to present their data and draw conclusions. Ask pupils to evaluate their work and draw inferences for use in everyday contexts.

  devise a plan in which they make fair comparisons

  collect and present data

  draw conclusions which they relate to practical, everyday situations

  evaluate conclusions by considering how good (valid) a model their house is

   This activity may be done as a complete investigation. Home insulation usually prevents a combination of conduction, convection and radiation. Pupils may confuse the various processes and methods, eg putting shiny foil on the wall behind a radiator reduces loss by reflection of radiation and, consequently, loss by conduction through the wall, even though the foil is a thermal conductor.

Safety

teachers should check any heating set-up before use

   KS3 Physics:  Checking progress

   to locate information from text and identify key points

   to show relationships between ideas by using links that show purpose and reservation

   Provide pupils with information sources so that they can discuss the pros and cons of different ways of insulating a typical home, eg using manufacturers’ claims for double glazing. They should attempt to explain their ideas using particle explanations and the concept of heat transfer through materials.

  produce a report explaining the way different ‘heat-saving’ methods work and comparing effectiveness

   Extension: pupils could consider the environmental impacts of the materials used to make and install insulators, eg cavity-wall foam, upvc window frames, etc.

    KS3 Physics: How can we explain change of state?

   to use the particle model to explain changes of state

   that solids, liquids and gases can change when energy is added or removed and these changes are reversible

   that changes of state occur at fixed temperatures

   to draw an appropriate curve/line to fit quantitative data on a graph

   Ask pupils to use the particle model to predict what might happen if heating of a solid or a liquid eg wax, water, continued indefinitely.

   Use ICT simulations to illustrate the particle model explanation for melting, boiling, freezing/solidifying.

   Invite pupils in groups to measure and record every half minute the temperature of one (or more) material as it changes state, eg

    ice as it melts

    water as it boils

    salol (phenyl salicylate) as it melts

    salol (phenyl salicylate) as it freezes

   Ask pupils to plot their data on a graph and show them how to draw an appropriate curve, or use temperature probes with a datalogger, to produce a real-time graphic display. Ask pupils to describe or tell the story of what happens to the temperature. Establish through discussion of their data and some data from secondary sources that changes of state occur at a fixed temperature. Challenge pupils to tell the story of what would happen if their particular substance were cooled or heated again.

  collect data and draw graphs with an appropriate curve to show what happens to the temperature as a material changes state

  use the terms ‘melting point’ and ‘boiling point’ and give some important examples

  describe what happens to the temperature of the substance, eg the salol got warmer and the temperature stayed the same for three minutes. When it had all melted, the temperature started to go up again

  describe, with reasons, what would happen if the liquid/ solid were cooled/heated again

  use the particle model to associate heating and cooling with changes of state

   At key stage 2, pupils will have had experience of changes of state and will have used scientific terms for these. They are unlikely to have discussed explanations in terms of particles.

   Negative numbers are introduced in key stage 1. By the end of key stage 2, pupils should be able to say that -100°C is lower than 50°C. However, they may need practice in adding and subtracting negative numbers.

   Some pupils may need help in choosing appropriate scales for the axes of their graphs.

Safety  

salol (phenyl salicylate) can be safely heated using a water bath;
it is not hazardous

     KS3 Physics: Reviewing work

   to use their ideas about the effects of heat transfer and particle explanations

   to communicate their ideas to a variety of audiences

   to interpret information

   Bring together pupils’ ideas developed in this unit by:

    – asking them to produce a leaflet which gives an example and an explanation of heat transfer in a situation of interest to them, eg on a mountaineering expedition above the snowline; on a beach holiday; cooking on a barbecue. Encourage imagination and ask for explanation. The audience for their leaflet may be parents, younger pupils, the general public

    – providing a large picture of a seaside scene including sea, sand, Sun, sunbather, beach barbecue, parasol, swimmer, balloonist and onshore wind. Ask pupils to identify all the situations of energy transfer and which mechanism is responsible, and to label and explain each item briefly

  show by their writing that they have assimilated the key ideas behind conduction and insulation

  synthesise the key ideas about heat transfer in their responses to the picture

 

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 Doc Brown's Revision  KS3 Science KS3 PHYSICS Unit 8J Magnets and electromagnets

KS3 Physics: About the unit

In this unit pupils:

  identify magnetic materials, make a magnet and test the strength of a magnet

  use the concepts of a magnetic field, a permanent magnet and an electromagnet

  investigate factors affecting the strength of an electromagnet

  explain the working of a number of devices that use magnets and electromagnets

In scientific enquiry pupils:

  use scientific knowledge and understanding to make predictions about the behaviour of magnets and magnetic material

  use preliminary work to find out whether an approach is practicable

  investigate the strength of an electromagnet, controlling relevant variables and evaluating the limitations of the data collected

Where the unit fits in

This unit builds on work done in unit 3E ‘Magnets and springs’ in the key stage 2 scheme of work and on unit 7J ‘Electrical circuits’.

It lays the foundation for unit 9I ‘Energy and electricity’, which includes the generation and uses of electricity.

KS3 Physics: Expectations

At the end of this unit

in terms of scientific enquiry

most pupils will: make predictions about the behaviour of magnets and magnetic materials and draw conclusions from patterns in evidence; identify factors affecting the strength of electromagnets, make sufficient observations in an investigation of electromagnets to draw conclusions

some pupils will not have made so much progress and will: suggest how to carry out a test to distinguish between magnets and magnetic materials; make changes to vary the strength of an electromagnet

some pupils will have progressed further and will: use a model of the magnetic field to explain phenomena

in terms of physical processes

most pupils will: distinguish between magnetic and non-magnetic materials; describe magnetic shielding; make a permanent magnet and an electromagnet; describe how the Earth’s magnetic field can be used for navigation; describe the shape and direction of a magnetic field; give examples of the use of magnets and electromagnets

some pupils will not have made so much progress and will: identify steel, iron and iron oxide as magnetic materials; make a magnet and electromagnet; describe the use of an electromagnet in sorting metals

some pupils will have progressed further and will: explain how magnetic materials can be magnetised using a simple particle/domain model; identify similarities in the magnetic fields of a bar magnet, the Earth and a straight coil; describe the shape of the field around a straight current-carrying conductor

KS3 Physics: Prior learning

It is helpful if pupils:

  know that magnets attract magnetic materials

  know that magnets can attract and repel other magnets

  know that magnets have a range of uses in everyday life, eg fridge door catches

  have constructed simple circuits and used power supplies

KS3 Physics: Health and safety

Risk assessments are required for any hazardous activity. In this unit pupils:

  use high currents at low voltage

Model risk assessments used by most employers for normal science activities can be found in the publications listed in the Teacher’s guide. Teachers need to follow these as indicated in the guidance notes for the activities, and consider what modifications are needed for individual classroom situations.

KS3 Physics: Language for learning

Through the activities in this unit pupils will be able to understand, use and spell correctly:

  words and phrases relating to magnets and electromagnets, eg north-seeking pole, south-seeking pole, magnetic field, magnetic field line, core, solenoid, coil

  words and phrases relating to scientific enquiry, eg qualitative and quantitative observation, range, precision, variable, trials, repeats

KS3 Physics: Resources

Resources include:

  sheets of magnetic material, eg steel, nickel

  materials for making permanent magnets and electromagnets

  secondary sources on the discovery of the Earth’s magnetic field

KS3 Physics: Out-of-school learning

Pupils could:

  think about how aluminium and metal cans are sorted for recycling and/or visit a scrapyard to see magnets

  observe the use of magnetic tags fitted to clothes to prevent shoplifting in clothes shops

    KS3 Physics: What can a magnet do?

   that magnets attract magnetic materials – iron, steel, nickel and cobalt, but not other metals – and magnetic iron oxide

   Elicit pupils’ ideas about magnets from their key stage 2 work about magnets, what they can do and where they are used. This can lead to the compilation of a class list of the types and uses of magnets, which will be added to as the unit progresses.

  name materials that magnets attract

  make a record of uses of magnets 

   Some pupils think all metals, and only metals, are magnetic. Introduce non-magnetic metals and ceramic magnets, which contain iron oxide.

   that like poles of a magnet repel and unlike poles attract

   that repulsion is the test of a magnet

   to use scientific knowledge to solve a problem

   to listen and evaluate the contributions of others

   Offer groups of pupils two magnets and a bar of steel of similar appearance. Challenge them to work out which one is not a magnet.

   Ask each group to describe and explain what they did and encourage other pupils to ask questions of them.

  state that magnets both attract and repel each other

  explain why attraction is not proof of magnetism

  describe, eg orally, their technique for deciding which bar was a magnet

   Pupils will be familiar with magnets attracting and repelling from key stage 2, but may not be familiar with the notion of magnetic poles.

 KS3 Physics: Can magnetism be stopped? Can magnets be made?

   that magnetic forces act through non-magnetic materials but not through magnetic materials

   Ask pupils to recall whether magnetism will act through any materials, using evidence they have from everyday life, eg fridge magnets, games such as magnetic football.

   Ask pupils to devise a test to see which materials allow magnetism to act through them, eg when a thread is attached to paper clip and taped to a bench, the paper clip will ‘hover’ below a magnet and fall when a sheet of magnetic material is inserted between it and the magnet. Ask pupils to suggest what the materials have in common to prevent the magnet working.

  describe how they found out that magnetic materials block the action of magnetic fields

 

   that magnetic materials can be made into magnets by stroking them with the pole of a magnet

   about the reasons for repeating observations

   to use observations to draw conclusions

   how discussion helps clarify ideas

   Establish that those materials which shield magnetism can be made into magnets, eg pupils make ‘soft’ iron nails into magnets using the stroking technique and test the magnet’s effectiveness. This could include a competitive aspect with a prize for the strongest magnet. Pupils could discuss and agree how the magnets’ strength is to be tested, eg number of paper clips picked up, numbers of trials to be carried out.

  describe how to magnetise a magnetic material

  design and use a method for measuring magnetic strength

   Pupils may have tested the strength of permanent magnets in key stage 2, so concentrate on the criteria which enable good comparisons to be made, eg sensitivity (Are paper clips too big?)

   Extension: the domain theory of magnetism is not included at this point, but a simple version could be given to some pupils.

    KS3 Physics: What is a magnetic field?

   that a freely moving magnet comes to rest pointing in a
north–south direction

   that all magnets have a magnetic north-seeking pole and south-seeking pole 

   Elicit pupils’ ideas about the Earth’s magnetic field. Draw on their experience of a compass for direction finding. Elicit the idea that the Earth acts like a magnet. Explain that the polarities of the Earth’s magnetic poles are reversed relative to the geographic poles, as a consequence of the ‘opposite poles attract’ rule.

  recognise that the Earth has a magnetic field, which attracts a freely pivoted magnet to line up with it

   Many pupils think that the magnetic field and gravity are somehow linked.

   Extension: pupils could find out about William Gilbert, Queen Elizabeth I’s physician, who discovered that the Earth is magnetic.

   what to take into account when deciding which equipment to use 

   Ask different groups to devise and test various suspension techniques,
eg on a thread, by floating, for allowing a freely suspended magnet to line up north–south. Discuss how well it works and when it could be used.

  identify that for magnets to point north to south, the suspension mechanism must be almost completely unaffected by other forces,
eg friction, moving air

  use appropriate equipment

   It is not necessary to demonstrate angle of inclination of the Earth’s magnetic field.

   that the area of force around a magnet is called a magnetic field

   that the magnetic field around magnets can be shown using iron filings

   that magnetic field line patterns show the relative strength of magnetic fields

   Demonstrate the toy which allows you to add hair to a face by moving iron filings using a magnet. Invite suggestions as to how it works.

   Use a magnet on the overhead projector (OHP), covered with a piece of perspex, to demonstrate the magnetic field lines around a single magnet, and also between magnets with like and unlike poles facing. Explain or show, eg using a ‘Magnaprobe’, that the field exists in three dimensions.

  recall the shape of the magnetic field line pattern around a bar magnet, eg strongest forces at the poles

  describe how the model of field lines shows that the field strength (magnetic force) falls as the distance from the magnet increases

   Field lines may be explored as a class practical, but this rarely gives satisfactory results unless the quantity of iron filings is limited and pupils know what to look for.

   Enclose magnets in plastic bags or cling film to stop iron filings from sticking to them.

   that the direction of the magnetic field can be plotted using compasses

   that the magnetic field lines can show the direction of the magnetic field

   to convert ideas presented orally into diagrammatic form

   to make and test predictions based on their scientific knowledge

   Elicit pupils’ ideas about what would happen if you put a magnetic compass near a magnet and at various positions around the magnet. Invite them to generate a diagram which predicts where the compass needle will point at each position around the magnet.

   Ask pupils to test their ideas by plotting the field direction with correctly magnetised compasses and to decide how far their predictions are supported.

  extend the model of magnetic field lines to represent the direction of the field

  present their predictions and observations diagrammatically 

   Pupils often think that a compass will point directly towards a magnet from all positions.

   KS3 Physics:  Checking progress 

   to relate ideas about magnets and magnetism

   Bring together pupils’ ideas about magnets and magnetism by asking them to construct a concept map, using the terms encountered, eg magnet, magnetic field, field lines, north seeking, south seeking, attract, repel, Earth, and respond to a series of written or oral questions.

  show, by their responses, that they understand the key ideas and relationships between them

   A concept map shows connections between key ideas and is a useful diagnostic tool for assessing pupils’  understanding.

     KS3 Physics: How can electricity make a magnet?

   how to make and change the strength of an electromagnet

   to use their previous experience to decide whether a possible approach is practicable

   to consider how their methods of investigation could be improved

   Show pupils examples of solenoid coils acting as electromagnets, eg bell, buzzer, relay, etc. Ask them to make a coil, eg from insulated wire around a wooden dowel, and connect it to a low-voltage power supply and observe effects.

   Ask pupils to plan how to investigate the factors that affect the strength of an electromagnet. They could use iron cores or soft iron nails. Remind them of their investigation into the strength of the magnets they made. Discuss the best way of obtaining and presenting results so that conclusions can be drawn. Ask them to consider the limitations in their findings, eg range and precision of results, and to suggest improvements by comparing their methods with those of others.

  identify the factors that affect the strength of an electromagnet

  make an electromagnet

  make appropriate measurements and present data in a suitable form to draw conclusions

  identify strengths and weaknesses in their own methods

   Ensure the paper clips do not become magnetised during the experiment.

Safety

   electromagnet power supplies need quite high currents. Care should be taken to ensure that this investigation does not fuse the power supply or melt the plastic insulation

   how electromagnets are used in domestic and industrial devices, eg electric bells, lifting magnets, relays

   to use sources of information independently

   to present information concisely for an audience

   Provide pupils with access to a range of resources on electromagnets,
eg models, devices and CD-ROMs, and ask them to report on how one application works,
eg orally or using diagrams.

  recall that electromagnets are used in a wide range of applications and show their understanding of electromagnetism through their report of how a device works

   Pupils could use a CD-ROM for their presentation.

   KS3 Physics:  How can we explain how electromagnets work?

   that wires carrying an electric current produce a magnetic field

   that the current in a coil produces a magnetic
field pattern similar to that of
a bar magnet

   that the strength of an electromagnet is increased by the presence of an iron core

   Use an OHP and/or compass to demonstrate that an electromagnet has a magnetic field pattern similar to permanent bar magnets. Ask pupils to predict whether there is still a magnetic field when the iron core (the only magnetic material present) is withdrawn. Demonstrate and ask pupils to use their knowledge of magnetic materials to explain why the electromagnet’s strength is far weaker without the core than with the core present. Relate this to pupils’ findings in their investigation.

  draw the field pattern of an electromagnet made from a straight coil

  explain the effect of an iron core, using ideas of magnetising materials

   This work links to unit 9I ‘Energy and electricity’.

   Extension: pupils could predict what the effect of straightening out the wire would be, then demonstrate the circular field pattern along the length of the wire using a perspex platform, above an OHP, on which to show the field.

     KS3 Physics: Reviewing work

   to summarise and make connections between key ideas

   Ask pupils to construct a series of ‘key facts’ cards based on information about the types of magnets and their uses that they have compiled during this unit.

  produce a set of succinct ‘key facts’ cards

 

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 Doc Brown's Revision  KS3 Science KS3 PHYSICS Unit 8K Light

KS3 Physics: About the unit

In this unit pupils:

  build on their knowledge of light and its effects

  learn how we see objects

  represent light as a ray and use this concept to explain reflection and refraction

  find out about the origin of coloured light and the appearance of coloured objects

In scientific enquiry pupils:

  consider why the spectrum described by Newton has seven colours

  make and test predictions about the path of light

  measure and record angles

  identify and make predictions from patterns in data

  investigate reflection and refraction at a plane surface

  investigate the effects of coloured light on the appearance of objects

Note

Much of this work involves the interpretation and analysis of visual information gathered from a variety of sources. Visually impaired pupils will be able to take part in activities through careful use of their residual vision and sense of touch, as many light sources are also heat sources. Teachers could adapt the work on colour to ensure that any pupils with impaired colour vision can make a contribution that is valued by the rest of the class.

KS3 Physics: Where the unit fits in

This unit uses ideas developed in the key stage 2 programme of study. It builds on ideas introduced in unit 3F ‘Light and shadows’ and unit 6F ‘How we see things’ in the key stage 2 scheme of work.

Sound travel is compared to light in unit 8L ‘Sound and hearing’. The drawing of objects in different lighting conditions is covered in unit 8A ‘Objects and viewpoints’ in the art and design scheme of work.

KS3 Physics: Expectations

At the end of this unit

in terms of scientific enquiry

most pupils will: make measurements of light intensity using a light sensor and compare the effects of materials on light; make predictions about the reflection of light at plane surfaces, measure angles with precision and make generalisations from the data; frame a question about light and colour and plan how to investigate it

some pupils will not have made so much progress and will: classify materials as opaque, transparent, translucent, reflectors or absorbers, on the basis of data from light sensors or visually; identify patterns in angular measurements of reflected rays of light; with help, investigate a question about colour and light

some pupils will have progressed further and will: draw conclusions from their data, informed by scientific understanding about reflection and refraction of light at plane surfaces; make predictions about image formation using the law of reflection or the patterns of behaviour from refraction; make sufficient observations when investigating colour to draw valid conclusions

in terms of physical processes

most pupils will: recognise that light travels in straight lines at very high speed; represent the path of light by rays; describe how light is reflected and refracted at plane surfaces; explain the origin of colour in the dispersion of white light and describe the effects of coloured filters and different coloured lights on the appearance of coloured objects; give an example of how colour is important in everyday life

some pupils will not have made so much progress and will: describe how light is reflected at plane surfaces and describe reflected images; describe the effect of a prism on white light and recognise that filters and coloured objects absorb some colours and transmit or reflect others

some pupils will have progressed further and will: calculate the time for light to travel,
eg from the Sun; explain the appearance of coloured objects in coloured lights

KS3 Physics: Prior learning

 It is helpful if pupils:

  know that light travels from a source

  can distinguish between opaque, transparent and translucent materials and relate shadow formation to opaque materials

  know that light is reflected from shiny surfaces

  know that we see things only when light from them enters our eyes

KS3 Physics: Health and safety

Risk assessments are required for any hazardous activity. In this unit:

  a laser may be used to demonstrate how light travels

  pupils use ray boxes

Model risk assessments used by most employers for normal science activities can be found in the publications listed in the Teacher’s guide. Teachers need to follow these as indicated in the guidance notes for the activities, and consider what modifications are needed for individual classroom situations.

KS3 Physics: Language for learning

Through the activities in this unit pupils will be able to understand, use and spell correctly words:

  relating to the behaviour of light and its interaction with materials, eg transparent, opaque, spectrum, reflection, refraction

  with similar but distinct meanings in everyday use, eg image, reflection

KS3 Physics: Resources

Resources include:

  pictures showing luminous and non-luminous objects

  secondary sources to find out about optical devices and phenomena, including reference books and CD-ROMs

  software simulation of colour mixing

  datalogger and light sensor

  a range of glass blocks of different shapes

  coloured filters and objects

  laser (class 2)

  infrared remote control device, eg from audiovisual (AV) equipment

KS3 Physics: Out-of-school learning

Pupils could:

  look for reflective materials in different situations, eg on road signs, safety clothing

  think about how an infrared remote control device for a TV works

  observe the effects of coloured lighting in shops, in theatres and on TV

     KS3 Physics: How does light travel?

   that light travels from a source

   that light travels at a very high speed, much faster than sound

   Review pupils’ understanding of light by asking them Where is there light in this room? Help them to develop the idea of light travelling and to recognise that although, when a light is switched on, its effects on objects seem instantaneous, this is because light travels at immense speed. Recall their experience of thunder and lightning, to show that light travels much faster than sound.

   Ask pupils for suggestions on how we could show that light moves, eg how a lighthouse works. Help pupils to carry out a thought experiment. Ask them to imagine what would happen if the source were moved further and further away from an object, and help them to understand that, at great distances, there is a lapse of time between leaving one and meeting the other. Some will have heard of the speed of light. Help them towards an understanding of this very large number by relating it to everyday speeds and distances, and comparing these with the distance between stars.

  recognise that light is all around

  state that light travels much faster than sound  

   Some pupils respond to the question Where is there light in this room? by identifying light sources rather than the idea that light is all around. Recognition that light radiates from a source implies that it is moving. Some pupils may believe that this movement of light applies only to very strong sources, eg the Sun, and that light from a weak source, eg a torch bulb, is different and slower.

   The speed of light is 300,000 km/s, and it thus takes light from the Sun 8.5 minutes to reach Earth, and reflected light from the Moon 1.3 seconds. Light from the nearest star (other than the Sun) takes
4 years to reach us.

   In unit 7L ‘The solar system and beyond’ pupils will have considered the solar system and stars. They will not have considered distances in terms of light.

    KS3 Physics: How does light travel? (Cont.)

   to interpret evidence and draw conclusions from it

   that light travels in a straight line

   that the path of light can be represented by rays

   Carry out a range of quick activities designed to develop the idea that light travels in straight lines, eg producing a shadow from a strong source, trying to look down a piece of rubber tubing, showing images of light rays shining through clouds, light rays in a mist, spotlight beams, light beams being reflected in a mirror. Encourage pupils to try to explain these phenomena in terms of a sequence beginning with light leaving the source and finally hitting a screen. Help pupils to use the idea of light travelling in straight lines in their explanation.

   Demonstrate how we can test the idea by shining a beam of light through a series of holes in pieces of card arranged one behind the other. Reinforce this concept by showing a laser beam and sprinkling talc or chalk dust in its path.

   Introduce the use of rays to represent light and ask pupils to draw diagrams of the evidence they have seen, using such lines to show the path taken by light in each case.

  describe evidence to support the idea that light travels in a straight line

  represent simply the path of light as rays 

   In key stage 2 pupils will have explored rays and beams of light. They are less likely to have produced explanations for phenomena in terms of light travelling in straight lines, or to have constructed ray diagrams.

Safety  

lasers should be class 2 and obtained from a reputable supplier. Laser pointers are usually class 3 and so are unsuitable

    KS3 Physics: What happens when light meets an object?

   that materials may be transparent, translucent or opaque

   to use ICT to make measurements

   that light may be absorbed, transmitted or reflected when it hits an object 

   Provide a range of materials for pupils to sort into transparent, translucent or opaque groups, by shining light from a ray box onto them. Ask them to explain what is happening to the light in each case, and introduce the ideas of reflection, transmission and absorption.

   Extend this work by allowing pupils to use a light sensor with a datalogger to compare the amount of light that is reflected by or transmitted through the different materials.

   Establish that materials reflect or transmit different amounts of light and ask pupils to suggest what has happened to the rest of the light, developing the idea of absorption.

  use words precisely when describing the effects of materials, eg transparent, translucent, opaque, reflect, absorb

  use a light sensor to make comparisons

  explain that some light may
be absorbed when it hits an object 

   Pupils will have carried out similar work during key stage 2, but this work provides a useful opportunity for pupils to use ICT and to introduce the concepts of reflection, transmission and absorption, which will be developed in other activities.

   Draw attention to materials that both reflect and transmit light.

   Extension: pupils could find out how bar-code readers work.

Safety  

if school-produced ray boxes are used, they must be checked for electrical safety by a Portable Appliance Test

    KS3 Physics: How do we see things?

   that we see non-luminous objects because light is reflected from them and enters our eyes

   to represent the path of light by rays

   Elicit pupils’ ideas about how we see things. Use their views to develop the idea that light travels into our eyes from luminous objects for us to see things. Extend this to non-luminous objects.

   Provide pupils with a picture containing luminous and non-luminous objects, and ask them to draw in some of the light rays that enable us to see these objects.  

  explain how non-luminous objects are seen, using words, eg ‘because light is reflected from them and enters our eyes’, and ray diagrams 

   At key stage 2 pupils are likely to have carried out activities illustrating that they see light sources when light from them enters the eyes. However, pupils may retain an ‘active eye’ model of seeing and draw rays travelling from the eye towards the seen object.

   Encourage pupils to represent the path of light as a single ray.

   Extension: pupils could imagine people in a mirrored room, eg dance studio/gym, and draw lines to show how objects can be seen both directly and by reflection.

    KS3 Physics: How do mirrors reflect light?

   that light is reflected from plane surfaces in a predictable way

   to make accurate measurements

   to represent data graphically and draw a line of best fit

   to draw a conclusion from data and to say whether it matches their prediction

   Introduce reflection using a torch in a darkened room. Ask pupils to predict where reflected rays will go.

   Demonstrate the use of a ray box and slit to produce a thin beam of light. Ask pupils to predict what will happen if the beam shines onto a plane mirror, to record their prediction, and to plan how to investigate their predictions of reflections at such a surface. Point out the need for accurate measurement and show them how to measure angles of light rays with reference to the normal, using a protractor, and to draw a line graph of their results. Through questioning, establish whether the data collected supports the pupils’ predictions.

   Ask pupils to find out how infrared remote-control devices work and whether infrared is reflected in a similar way to light.

  make predictions about the way that light is reflected from plane surfaces

  make and record accurate measurements of angles of incidence and reflection with respect to the normal

  represent the data as a line graph and draw a line of best fit

  make a generalisation, eg the light is reflected from a plane surface at the same angle at which it hits it

   These activities provide a good opportunity for making, testing and refining predictions in a simple situation.

   At key stage 2 pupils are likely to have investigated reflection by mirrors, but they will not have drawn ray diagrams and measured angles.

    KS3 Physics: How are images formed?

   that when light is reflected from plane surfaces an image is formed

   to make and test predictions about reflections

   to make and test predictions about the number of images formed in paired mirrors

   Introduce the idea of the nature of a ‘mirror image’ produced in a plane mirror. Ask pupils how such an image differs from the object viewed, and explore their explanations of why this happens, eg pupils could, in pairs, model object and image in a mirror.

   Ask pupils to explore the symmetry of images by predicting and testing which capital letters or words are symmetrical and by predicting the number of images formed of an object placed between two plane mirrors set at different angles.  Encourage pattern seeking so that pupils can make predictions. Show how to ‘see yourself as others see you’ in two mirrors set at 90° to each other.

  describe the nature of the image formed in a plane mirror, eg inverted

  suggest how such an image is formed

  make and test predictions about the number of images formed in mirrors

  record findings, describing patterns in these

   Although the mirror image appears to be laterally inverted, this presents the problem of why it is not inverted top to bottom as well. It would be more accurate to say the mirror inverts ‘back to front’. This can be demonstrated by writing on an overhead transparency (OHT), holding it in front of a mirror and looking through it at its reflection.

   The relationship of the angle between the mirrors (A) to the number of images (N) is expressed as A(N+1) = 360. It is helpful to suggest that pupils initially investigate angles that are factors of 360.

    KS3 Physics: Checking progress

   to apply understanding of reflection to everyday situations

   Present pupils with a range of examples of how reflections are used and ask for explanations of how they work, eg reflective cycle clothing, reversed ambulance signs, kaleidoscope, periscope, Pepper’s ghost.

  explain everyday reflections using words and/or ray diagrams

   CD-ROMs and internet sites provide useful support for these aspects of light/optics. The kaleidoscope was invented by the Scottish physicist David Brewster as a design aid.

   Extension: pupils could practise drawing in a mirror, eg following the shape of a star, looking only in a mirror.

    KS3 Physics: Can light be bent?

   that light changes direction at a boundary between two different media

   to identify patterns in observations

   to apply understanding of refraction to everyday situations

   Demonstrate simple situations involving refraction, eg pencil in beaker of water appears to bend, and the strange views perceived when looking through water, eg in a swimming pool. Introduce the idea of light changing direction when it passes from one transparent medium to another, and the term ‘refraction’, and distinguish this from reflection. Help pupils to interpret what they see by explaining that they imagine light as having travelled in a straight line rather than as having been refracted (bent).

   Provide a range of glass or perspex blocks of different shapes, including rectangular and semicircular, and ask pupils to investigate their effects on a single ray of light produced by a ray box. Ask them to look for patterns in their observations of reflection when changing the angle of incidence. Establish generalisations from patterns of observations.

   Set up the ‘disappearing coin in a cup of water’ demonstration. Ask pupils to explain how it works.

  make generalisations from their observations of refraction, eg that a change of direction occurs only at an interface; light bends towards the normal (inwards) when travelling from a more dense to a less dense medium, and vice versa

  draw selected angles of incidence and refraction and use these to establish generalisations, eg when the ray travels from air to glass, the angle of refraction is smaller than the angle of incidence

  draw a ray diagram to explain a phenomenon of refraction

   Aboriginal peoples learn to compensate for refraction when spearing fish.

   Pupils may need help if they try to draw ray diagrams illustrating refraction.

   At this stage, it is sufficient to establish the idea of refraction. Snell’s law is not required, so it is best to avoid measuring, as pupils will look for a numerical relationship (and find unhelpful ones).

    KS3 Physics: What is a spectrum?

   that white light can be dispersed to give a range of different colours

   why the spectrum has seven colours

   to use scientific knowledge to suggest reasons for physical phenomena

   Demonstrate how white light can produce a spectrum when shone through a prism, and describe the work of Isaac Newton in this field. Ask questions about colours, eg Can you really see seven colours?

   Provide pupils with prisms and ask them to explore and record the images they see in them.

   Allow pupils to make their own spectrum and challenge them to suggest how the coloured rays could be remixed. Help them to achieve this, using a second prism, and develop the idea that white light consists of a mixture of different coloured lights, which can be separated and combined.

  identify the colours of the spectrum

  describe how white light is dispersed by a prism to give a range of different colours

  describe how a spectrum can be recombined to form white light

   Most people cannot distinguish indigo in the spectrum, and it is thought that Newton included this because of his belief in the mystical significance of the number seven.

   Extension: ask pupils to find out how a rainbow is formed.

    KS3 Physics: How can we change colour?

   how coloured filters change white light

   to combine knowledge from different sources to explain how coloured filters work

   how coloured light can be combined to produce new colours

   Ask pupils to explore how coloured filters affect light, eg by producing a spectrum and allowing this to pass through filters of different colours; by passing white light through one filter and then through a second filter.

   Remind pupils of their earlier work on absorption and transmission of light, and on the nature of coloured light as demonstrated by the spectrum. Ask pupils to explain why light appears to change colour as it passes through.

   Establish the idea that coloured filters will only transmit light of certain colours, the other colours being absorbed, and help pupils illustrate this with annotated diagrams.

   Demonstrate, using an overhead projector (OHP), software or video clips, how the primary colours of light can be combined to produce white light, and briefly discuss the relevance of colour vision and the production of coloured pictures on television.

  investigate how coloured filters change white light

  suggest how filters affect white light

  investigate how coloured light can be combined to produce new colours 

   Detailed understanding of colour vision is not required here.

   Most filters allow a mix of colours to pass through and results are often unconvincing. Have a set of primary colour filters on hand for demonstrations, ie spectral blue, green and red.

   In unit 8A ‘Objects and viewpoints’ in the art and design scheme of work pupils draw objects using different light sources and viewpoints.

   how coloured objects appear in white light and in different colours of light

   to use scientific knowledge and understanding to explain observations

   Ask pupils to investigate the effects of viewing different coloured objects in beams of light of different colours. They should collect a range of observations as a table, and try to find patterns in these. Ask pupils about applications of this effect, eg in disco lighting, in matching dyes in fabrics, in identifying colour of clothing under street lighting.

  investigate how coloured objects appear in white light and in different colours of light

  identify and explain patterns of their observations using appropriate vocabulary,
eg reflect, absorb, transmit  

   This activity is best carried out with objects in an enclosed box with a hole for viewing, to eliminate as much extraneous light as possible. Software simulations may provide more convincing ‘results’.

    KS3 Physics: Reviewing work

   to describe what happens to
a beam of light when it encounters a range of materials

   to use scientific knowledge and understanding to plan and to explain the reasons for their plan 

   Provide pictures of a series of mirrors, opaque materials and transparent blocks and ask pupils to complete the paths of a light ray incident on them.

   Ask pupils to design the lighting for a theatre production in which particular colour effects are desired, and to present their suggestions to the group or whole class.

   Ask pupils to describe and explain any optical effect that has particularly impressed them, eg laser display.

  describe, using annotated diagrams and the correct scientific terminology, how the path of light can be altered by reflection or refraction

  present an account of the use of colour in creating particular effects

 

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 Doc Brown's Revision  KS3 Science KS3 PHYSICS Unit 8L Sound and hearing

KS3 Physics: About the unit

In this unit pupils:

  build on their knowledge of sound and hearing

  explain how sound travels through media

  give an explanation of how the ear works, find out about the harmful effects of loud noise and how loud noise can be reduced

In scientific enquiry pupils:

  decide on a suitable question to investigate and on what type of data to collect

  identify relevant variables and consider how to control or take account of them

  evaluate data, considering alternative explanations

  investigate the loudness of sounds using an appropriate strategy

Note

Hearing-impaired pupils can make a valuable contribution to this unit, but will need particular support, eg by visual demonstrations of vibrations when sounds are produced, the use of amplification apparatus or ICT to translate sound into visual information. The work at the end of the unit on hearing impairment can be adapted if there are hearing-impaired pupils in the class, to ensure their contribution is valued by the rest of the class.

KS3 Physics: Where the unit fits in

This unit uses ideas developed in key stage 2. It builds on unit 5F ‘Changing sounds’ in the key stage 2 scheme of work.

This unit could be linked with unit 7 ‘Measuring physical data’ in the ICT scheme of work, which suggests an investigation of an aspect of sound.

The elements of musical sounds are covered in unit 3 ‘Soundscapes’ in the music scheme of work.

The wave nature of sound is further developed in key stage 4.

KS3 Physics: Expectations

At the end of this unit

in terms of scientific enquiry

most pupils will: identify patterns in qualitative data about sound and describe sound qualities; frame a question about hearing which can be investigated; identify and control key variables; identify limitations in their data; compare sound levels, and report on a loudness enquiry; describe a current issue related to sound

some pupils will not have made so much progress and will: measure sound levels and describe a range of sounds; describe what they found out from an investigation into hearing; compare sound levels, and report on loudness of sound in common situations

some pupils will have progressed further and will: select an appropriate approach to investigating a question about hearing; present a reasoned argument about a current issue in the science of hearing

in terms of physical processes

most pupils will: relate changes in pitch and loudness of sounds to changes in vibrations; explain how musical instruments can make these changes and relate these to the oscilloscope representations of waves; recognise that sound needs a medium to travel through and that it travels at different speeds through different media; explain simply how the ear works and give examples of hearing ranges; describe ways in which hearing can be impaired and how noise pollution can be reduced

some pupils will not have made so much progress and will: relate sound to vibration and identify a range of sources or vibrations; recognise that sound travels but cannot travel through a vacuum; explain that sound waves cause our eardrums to vibrate and that this enables us to hear; state that loud sounds can damage hearing

some pupils will have progressed further and will: relate pitch to frequency of sounds and loudness to amplitude; use particle theory to explain how sound travels through materials; use a model of the ear to discuss possible causes of hearing impairment

KS3 Physics: Prior learning

It is helpful if pupils know:

  that sounds are produced by vibrating sources

  how the sounds produced by musical instruments can be changed

KS3 Physics: Health and safety

Risk assessments are required for hazardous activity. In this unit pupils:

  use sound sources which could exceed recommended safe levels

  may work near traffic and require supervision

Model risk assessments used by most employers for normal science activities can be found in the publications listed in the Teacher’s guide. Teachers need to follow these as indicated in the guidance notes for the activities, and consider what modifications are needed for individual classroom situations.

KS3 Physics: Language for learning

Through the activities in this unit pupils will be able to understand, use and spell correctly:

  words and phrases describing features of sound, eg loud, soft, quiet, high, low, pitch, noise pollution, temporary deafness

  words to describe sound vibrations, eg frequency, amplitude, wave

  words with different meanings in scientific and everyday contexts, eg quiet, soft, low, pitch, wave, loudness, volume, dynamics

  words and phrases relating to scientific enquiry, eg qualitative data, alternative explanations

Through the activities pupils could:

  understand information that is not explicitly stated or that the reader is assumed to understand

KS3 Physics: Resources

Resources include:

  musical instruments (actual and illustrations of), eg stringed, wind, percussion

  means of generating, capturing and displaying representations of sound waves, eg tuning forks, signal generator, microphone, loudspeaker, oscilloscope, datalogger, or computer with sound card

  radio or audio tape player

  data about sound levels, eg from the Noise at Work regulations; data about hearing loss in different age groups and accounts of temporary deafness or tinnitus

KS3 Physics: Out-of-school learning

Pupils could:

  think about how the musical instruments that they play or listen to make sounds

  think about the loud and distracting noises in the environment

  consider the effects of loud noise on hearing

  look for safety signs and warnings about loud noises

  ask family members or friends who play traditional instruments to demonstrate them

    KS3 Physics: How are different sounds made?

   to use appropriate language to describe different sounds

   that sounds are made as a result of vibrations 

   Review pupils’ knowledge and understanding of sound. Play an audio tape of different sounds, and ask pupils to identify and/or describe them. Check they use associated words correctly, eg ‘high’ and ‘low’ to describe pitch, and ‘loud’ and ‘soft’ to describe intensity.

   Ask pupils how sound is produced. Show pupils examples where the vibration is easily seen, eg tuning fork and polystyrene ball, loudspeaker and grains of sand. Provide familiar sound sources or pictures, eg musical instruments, and ask pupils to identify which part(s) vibrate(s) to make the sound.

  describe different sounds using appropriate terms,
eg high, low and soft

  explain that sounds are made as a result of vibrations and identify the source of vibration in a range of cases 

   This activity is intended to help teachers find out what pupils know
and understand about sound from
key stage 2.

   Some pupils may confuse the use of sound words, eg low for soft, and high for loud. Working through examples to reinforce the concepts of pitch and intensity may be required to overcome this.

   In music the loudness (volume) of a sound  is one of the elements, called the ‘dynamics’ of the sound. The opposite of loud is quiet; soft refers to the quality or timbre of the sound.

   how to change the pitch and loudness of sounds from musical instruments

   to describe patterns in qualitative data and make generalisations from these

   to relate changes in sound to changes in vibrations

   Demonstrate, eg with a guitar, recorder and drum (adjustable tension), how notes of different pitch and loudness can be made.

   Ask pupils to investigate differences in the vibrations that produce the sounds in musical instruments, and help them to make generalisations.

   Reinforce these ideas by showing how pulling down further on a mass suspended from a spring makes the oscillations bigger, and how using a larger mass makes the oscillations slower. Discuss with pupils how these observations relate to their work on sound-producing vibrations.

  suggest ways to change the pitch and loudness of sounds from musical instruments

  make generalisations about changing sounds in musical instruments, eg the thinner the string, the higher the sound

  make generalisations about changing sounds related to vibrations, eg the greater the movement, the louder the sound; the faster the movement, the higher the sound

   Pupils who play a musical instrument could be asked to demonstrate it to the class.

   The use of instruments from a variety of cultures, eg sitar, tabla, pan pipes, provides an opportunity to broaden the range of evidence about changing sounds in musical instruments.

    KS3 Physics: How are different sounds made? (Cont.)

   to use appropriate scientific language to describe features of a sound wave

   that sounds with high pitch have a high frequency

   that sounds with a high amplitude are loud

   to relate their results to scientific knowledge and understanding 

   Extend pupils’ ideas about sounds and vibrations using an oscilloscope connected to a signal generator (or a microphone connected to a datalogger) to present a ‘picture’ of a sound wave. Explain that the wave on the screen is a representation of a sound wave. Introduce and explain the terms ‘amplitude’ and ‘frequency’, and relate these to loudness and pitch of a sound by demonstrating how the wave form changes with different sounds. Provide representations of different sound waves and ask pupils to identify, eg the loudest, lowest.

  use the terms ‘frequency’ and ‘amplitude’ in describing sound waves

  relate high pitch to high frequency and high amplitude to loudness

  compare and interpret wave forms in terms of pitch and loudness 

   A brief account of what is happening in the oscilloscope is all that is needed at this point, if pupils are not to be distracted by the details of the display system. Pupils may use an oscilloscope to study the features (elements) of sounds in unit 3 ‘Soundscapes’ in the music scheme of work.

   A detailed account of the longitudinal nature of sound waves is left until key stage 4. At this stage you will need to make sure that pupils have not gained the erroneous idea that sound waves are transverse. A quick demonstration using a slinky spring might be helpful.

   Extension: show pupils the wave representation produced by different sources of sound, eg tuning forks, musical instruments, and ask them to identify and try to explain similarities and differences.

    KS3 Physics: How does sound travel through solids, liquids and gases?

   how the vibrations that make sound are transferred through a medium

   that sound cannot travel through a vacuum

   to relate sound travelling through a medium to the particle model

   that sound travels at different speeds in different types of material

   to use the particle model to explain how sound travels

   Establish that sound needs a medium to travel through. Show pupils an electric bell ringing inside a bell jar. Ask them to predict what will happen if the air is pumped out of the jar, and test their predictions. If the pump is noisy, it would be better to listen as air is let back in.

   Ask pupils whether sound travels through solids, eg Can you hear through closed doors? Can animals hear under water? Ask pupils to carry out some quick activities to demonstrate transmission of sound through solids and liquids, eg battery-operated radio in sealed plastic bag under water using a hydrophone, sound passing through a wooden bench, a length of metal rod, a string telephone. Help pupils to make comparisons with sounds from the same source transmitted through air and establish that transmission is more effective through denser media. Ask pupils why this may be so, reminding them of the particle model of solids, liquids and gases. Help pupils to record what they found out, eg using annotated diagrams.

   Remind pupils that sound travels much more slowly than light, eg fireworks. Ask them if sound travels at different speeds in solids/liquids/gases. Draw on experiences, eg singing railway lines before the train is heard through air, listening closely with an ear to a metal railing that is tapped some metres away. Ask how they might measure these differences. Quote the example of the two people who, some 100 years ago on Lake Geneva, measured the speed of sound in water. One made a visual signal while striking a bell under water. The other started his stopwatch and plunged his head in the lake until he heard the bell.

   Encourage pupils to explain the differences using the particle model.

  state that sound cannot travel through a vacuum but can travel through solids, liquids and gases

  describe how sounds travel through solids, liquids and gases

  explain in terms of the particle model why sound needs a medium

  explain how sound travels at different speeds in different types of material

  explain everyday phenomena in terms of the different speeds at which sound travels in air and solids

   Sound waves dissipate less energy when travelling through liquids and solids, compared with air. This allows them to travel more quickly and to retain intensity.

   Sound travels at 330ms-1 in air,
1500ms-
1 in water, and at higher
speeds in solids: 3000ms-
1 in brick and 5000ms-1
in iron.

   Unit 7G ‘Particle model of solids, liquids and gases’ and unit 7H ‘Solutions’ introduce pupils to the particle model.

   Unit 9K ‘Speeding up’ covers the measurement of speed. Pupils could measure the speed of sound as part of that unit.

   Extension: Pupils could make a hydrophone by stretching a thin sheet of rubber over the open end of a funnel connected to a length of rubber tubing.

    KS3 Physics: Checking progress

   to give explanations in answer to questions

   With the class, produce a list of key questions related to the work that has been covered. Ask pupils in groups to use secondary sources and their own notes to produce answers to five of these. Pick out any particularly challenging questions and discuss pupils’ answers to them with the class.

  use appropriate terminology, evidence and reasons in their answers

   CD-ROMs on sound would be useful for the review of the work in this section.

KS3 Physics: How do we hear sounds?

   that different people can hear different ranges of pitch

   that hearing changes with age

   that some animals detect sounds that are inaudible to human ears 

   Use an audio signal generator to generate a range of sounds of different pitch. Ask pupils to indicate when they can no longer hear the sound. Tell pupils about the range you can hear and ask why the teacher’s range of hearing is often more limited than that of pupils.

   Ask pupils what they know about the hearing range of animals and discuss how different animals use sound, eg long-distance communication in whales, ultrasonic echo location in bats, communication using whistles with dogs.

  describe how hearing ability changes with age and that hearing can be damaged

  describe examples of animals detecting sounds that are inaudible to human ears 

   Sensitivity is needed in talking about hearing impairment. There is an opportunity for a visit by an outside speaker concerned with the issues and problems faced by hearing-impaired people.

   The range of hearing for an adult is typically from 20Hz to 20,000Hz, but pupils may hear as high as 30,000Hz.

   that the energy of sound is transferred through the eardrum

   that the effects of vibration to the eardrum are transferred to the brain 

   Elicit ideas from pupils about how we hear sounds. Show them an anatomical model of the ear, illustrating the relative sizes of the parts and how they are connected.

   Explain how the eardrum vibrates as a result of sound entering the ear, and the transmission of vibrations to the inner ear. A model eardrum can be used to demonstrate the transmission of vibrations from the air to a membrane.

  identify the parts of the ear on a diagram or model

  describe, eg by annotating a diagram, how vibrations in the air are transmitted and translated into electrical signals, which pass to the brain  

   A full explanation of the working of the ear is not required. Work with pupils should concentrate on developing an understanding of the transmission of vibrations and their conversion to electrical signals, which pass to the brain.

   Make a model eardrum by removing the end of a plastic cup, and covering the hole left with clingfilm. The clingfilm will vibrate when you talk into the open end of the cup.

KS3 Physics: How do we hear sounds? (Cont.)

   how to frame a question that can be investigated

   how to decide whether measurements, qualitative observations, or data from secondary sources are appropriate

   to decide which factors in a particular investigation can be controlled

   to look critically at results and decide how strongly they show a relationship

   to compare their work with
the work of others, and to evaluate it

   Ask pupils to design and carry out an investigation into an aspect of hearing, eg

    Are two ears better than one in detecting the direction sound is coming from?

    Does the size of the outer ear affect hearing sensitivity?

    Does hearing range decrease with age?

   Help them to decide on a suitable question to investigate, and to plan their work, including consideration of variables, collection of suitable data and evaluation of results.

   Ask pupils to use overhead transparencies (OHTs) or a flip chart to summarise their work and to present it to other pupils. Encourage pupils to compare their own investigations with those of others and to identify good and bad points in them.

  decide on appropriate measurements to answer the question

  identify factors which need to be controlled if they are to make a fair test

  describe strengths and weaknesses in their work, eg We tested four people in each age group, but the results don’t show a clear pattern, so we need to test more people

   Pupils could find data from secondary sources as well as collecting first-hand data.

   Extension: pupils could use secondary sources, including reference books, the internet and CD-ROMs, to find out about the use of sound in interesting or novel contexts, eg how telephones or microphones work, how bats use ultrasound to navigate, how echo soundings are used by ships.

   KS3 Physics: Can sound be dangerous?

   how to compare loudness

   how to plan to collect data

   about reasons for repeating measurements

   to present data appropriately

   Raise issues of noise pollution, eg near airports, due to traffic and listening to pop music. Demonstrate use of a sound-level meter. Ask pupils about an alternative method of comparing sounds that relies on the way loudness diminishes with distance, eg measure the distance at which the sound first can no longer be heard. Ask pupils to investigate a question, eg

    survey the loudness of sounds at different locations around the school or over time in their own classroom

    compare the loudness of sounds from personal stereos, eg set at the level at which pupils like to listen

    investigate the effects of sound insulation, eg with a clock in a box filled with different absorbent materials

   Help pupils to plan the measurements (including repeat measurements) they will take and the way they will record and present their data.

   Present data from secondary sources on sound and recommended safe levels. Ask pupils to draw up a list of sound levels for common sounds.

  use a sound-level meter or other method of comparing sounds

  make a sufficient number and range of measurements

  present data and draw appropriate conclusions

   The decibel (dB) scale measures differences between sound power levels. It is expressed logarithmically to reflect the ear’s response. Sound-level meters use a modified scale called dB(A), which allows for the ear’s different sensitivity to different frequencies. Strictly speaking, loudness is measured in phons, but at this level pupils can use the sound-level meter values as measures of loudness. A datalogger could be used with the meter for measurements over time.

   This work could be linked with unit 7 ‘Measuring physical data’ in the ICT scheme of work.

Safety

supervision is required for any
work near traffic. Follow employer’s guidelines for fieldwork. Ensure sound levels are within permitted limits. Pupils’ plans must be checked for health and safety before practical work begins

   to use their scientific understanding to interpret secondary sources on a current issue

   Present information about noise pollution and ask pupils to suggest ways of reducing noise levels.

  report on a topic showing understanding of the nature of sound and hearing

 

    KS3 Physics: Can sound be dangerous? (Cont.)

   to consider how strongly the data supports any conclusion drawn

   to consider alternative explanations

   how loud sounds can damage hearing

   to understand information that is not explicitly stated or that the reader is assumed to understand

   Present pupils with information about hearing impairment, eg among different age groups, and ask them to suggest possible reasons, eg exposure to loud sounds at work, exposure to loud sounds when young, inherited deafness. Help pupils evaluate possible explanations and to think of reasons for supporting and rejecting them.

   Use some accounts of people’s experience of temporary deafness or tinnitus to discuss with pupils what excessively loud sound can do to hearing. Use a model or diagram of the ear to discuss what might cause the problems.

   Ask pupils to present their findings and views in the style of a popular medium, eg youth magazine, local radio item.

  explain why they think the data supports one explanation more than another

  describe sensations of temporary deafness or tinnitus and indicate how these arise

   Teachers will be aware of the need to be sensitive to individual pupils and to their families.

   The causes of tinnitus and temporary deafness are still a matter of debate, and probably involve both the ear and the brain. For details on current ideas search the internet, eg

    www.hearnet.com

    www.hhmi.org/senses/start

   Extension: pupils could be asked to find out about a range of questions, eg how some rock musicians protect their hearing, about the career of Evelyn Glennie, the renowned deaf percussionist, using an internet search, eg ‘hearing+loss’, ‘Evelyn+Glennie’.

    KS3 Physics: Reviewing work

   to relate ideas about sound and hearing to each other 

   Review work on sound and hearing by helping pupils construct a concept map using terms, eg pitch, loudness, amplitude, decibel, hearing, vibration, sound insulation. Discuss outcomes with pupils.

  make connections between different ideas within this unit

 

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 Doc Brown's Revision  KS3 Science KS3 PHYSICS Unit 9I Energy and electricity

KS3 Physics: About the unit

In this unit pupils:

  explore a range of useful energy transfers and transformations

  discuss the use of electricity as a convenient way to transfer energy to do useful things

  associate the concept of voltage with the transfer of energy in a circuit

  investigate the voltage of cells

  study how electricity is generated, with reference to environmental impacts

  use the principle of conservation of energy to identify ways in which energy is dissipated during transfers

In scientific enquiry pupils:

  use models to explain observations relating to electric currents

  use scientific knowledge to frame a question for investigation

  measure voltage in circuits

  identify patterns in the measurements of voltage in series circuits and use these to draw conclusions

Note on the teaching of energy

This unit presents a range of useful changes and helps pupils to use the language of energy transfer and transformation in describing them. The word ‘transfer’ is used to describe energy’s change of place; the word ‘transform’ is used to describe a change in the way energy shows itself, eg from electrical energy to light.

The unit focuses on how transfers and/or transformations of energy by electricity are important in everyday life. It explains these simply and looks at some of the consequences of the electricity supply industry. The unit covers the ideas of dissipation or ‘wasted’ energy and the conservation of energy. In extending the concept to these contexts, simplifications appropriate to year 9 pupils have been made.

Pupils need labels they can use when they come across energy, eg electrical energy, light and heat. This is a first step in developing understanding. Teachers should help pupils recognise that they need to go further in some contexts, eg that ‘spring energy’ is the result of the elastic properties of the metal the spring is made of, and so could be called ‘potential energy’ because of its compressed position. It would be inappropriate, at this stage, to develop this further and associate the energy with the electric bonding forces between the atoms of the spring. Formal definitions of work, kinetic energy and potential energy are also best left until key stage 4 for most pupils.

KS3 Physics: Where the unit fits in

This unit builds on work on electricity and energy in units 7I ‘Energy resources’, 7J ‘Electrical circuits’ and 8I ‘Heating and cooling’. It relates to work on the reactivity of metals in unit 9F ‘Patterns of reactivity’ and work on fuels in unit 9G ‘Environmental chemistry’. It relates to unit 9D ‘Using control for electronic monitoring’ in the design and technology scheme of work, and to unit 18 ‘Twentieth-century conflicts’ and unit 20 ‘Twentieth-century medicine’ in the history scheme of work.

KS3 Physics: Expectations

At the end of this unit

in terms of scientific enquiry

most pupils will: identify patterns in measurements of voltage and use these to draw conclusions about circuits; identify and control key factors in investigating simple cells and identify patterns in their results, including observations that do not fit the main trends

some pupils will not have made so much progress and will: measure the voltage of a range of cells; present data as charts or tables

some pupils will have progressed further and will: relate energy transfer devices in the laboratory to everyday appliances; synthesise information from secondary sources about the development of the electricity supply industry and communicate it clearly; consider whether data is sufficient, and account for anomalies

in terms of physical processes

most pupils will: describe some energy transfers and transformations in familiar situations, including dissipated energy, and devices; recognise that the voltage change across a circuit component is a measure of its energy transfer; describe how voltage originates from a chemical cell; give examples of the hazards of high-voltage circuits; compare the energy consumption of common electrical appliances; describe how electricity is generated by energy from fuels, and recognise possible environmental effects of this

some pupils will not have made so much progress and will: describe some useful energy transfer devices; recognise that any functioning circuit needs a power supply to provide a voltage and that high voltages are hazardous; recognise that electricity is a convenient way of ‘delivering’ energy, but that it must be paid for and that its generation can cause environmental problems; give examples of how energy goes to waste

some pupils will have progressed further and will: apply a model of voltage and energy changes to a circuit; recognise that although the total energy in a system is conserved, energy can be dissipated; use ‘power ratings’ in comparing the costs of using different electrical appliances; link the function of an electric generator to magnetic effects

KS3 Physics: Prior learning

It is helpful if pupils:

  know how to connect simple series and parallel circuits

  recall that fossil fuels and wind, waves and the Sun are all energy resources

KS3 Physics: Health and safety

Risk assessments are required for any hazardous activity. In this unit pupils:

  use mains electrical equipment in their investigations

Pupils must not experiment with mains electricity.

Model risk assessments used by most employers for normal science activities can be found in the publications listed in the Teacher’s guide. Teachers need to follow these as indicated in the guidance notes for the activities, and consider what modifications are needed for classroom situations.

KS3 Physics: Language for learning

Through the activities in this unit pupils will be able to understand, use and spell correctly:

  words and phrases relating to scientific enquiry, eg independent and dependent variable, control

  words and phrases describing energy transfers and transformations,
eg movement as kinetic energy, position as potential energy, chemical energy, electrical energy, sound, heat and light

  words and phrases relating to energy supply and waste, eg conservation, dissipation, electric generator, dynamo, power station

Through the activities pupils could:

  use secondary sources to assess conflicting evidence and arrive at a considered viewpoint

  write coherent text to communicate information effectively

KS3 Physics: Resources

Resources include:

  a selection of electrical toys and devices to show energy transfers and transformations

  samples of fruit and vegetables or dilute acid solutions

  a selection of samples of metals to make electrodes, eg copper, zinc, iron, aluminium, magnesium

  secondary source material on generating electricity and associated environmental issues, electric cars and other ‘energy-saving’ appliances

  small motors or materials to build generators

  a bicycle dynamo

  a joulemeter (and datalogger)

  ammeters and voltmeters or digital multimeters

  a household electricity meter or picture of one

  domestic appliances, including low-energy bulbs, or pictures of and energy information about these

KS3 Physics: Out-of-school learning

Pupils could:

  survey the power rating of various devices in the home or observe their electricity meter when different appliances are running

  check their own electricity bill

  keep a diary of energy experiences, eg Today I used my personal stereo with new batteries

KS3 Physics: How is energy involved in doing useful things?

   that useful changes usually involve energy transfers and transformations

   that the terms ‘kinetic’, ‘potential’, ‘radiation’ and ‘chemical’ are useful when describing energy

   Remind pupils of their experience of energy transfers and transformations in years 7 and 8 with demonstrations of ‘useful changes’, eg working a model steam engine, a spring-driven clock, eating food. Help pupils associate the presence of energy with the different situations in the demonstrations, eg steam-engine fuel, flame, hot water, movement, and to use the terms ‘kinetic’, ‘potential’, ‘chemical energy’, ‘heat’, ‘light’ and ‘sound’ as ways of describing energy in such situations.

  Ask pupils to explore a circus of toys and devices that work by transferring and/or transforming energy. Ask pupils to identify the source of energy and the use to which it is put. Include a range of electrical toys and devices, eg

battery-operated and clockwork/spring-operated vehicles

yo-yo (if possible one that lights up at maximum speed)

battery-operated and manually operated fans

electromagnet for lifting

– electric bell or buzzer

solar-powered calculator or motor

low-voltage heater that is set to get warm, not hot, to the touch

toys that feature light-emitting diodes (LEDs)

simple control circuit, eg one that sounds a buzzer when a light sensor is covered

  recognise that energy is routinely converted from one form to another in order to be useful

  categorise devices on the basis of type of energy input or output

  explain why electricity is used widely as a source of energy

  describe energy transfers in everyday changes

   The energy ‘transfers’ met in conduction in unit 8I ‘Heating and cooling’ can be contrasted with energy ‘transformations’ in these devices. Energy should, however, be associated with the situations rather than being described as different ‘types of stuff’. See the note on teaching energy in the Teacher’s guide.

   Potential energy is used to refer to energy associated with an object’s position, eg a stretched spring or a raised mass.

   that electrical circuits are used to perform a variety of useful tasks

   that electrical energy is transferred around circuits and can be transformed in components, eg to produce light, sound, movement and heat

   to identify devices and situations that act as energy stores

   Elicit from pupils’ observations the conclusion that electrical energy is a convenient way to do many useful things. Recall pupils’ year 7 work on fuels as energy stores and elicit other ways that energy can be stored, eg compressed spring – potential; flywheel – kinetic; battery – chemical. Contrast this with electricity, which cannot be stored.

  describe the energy transfers and/or transformations in several toys or devices

  recognise that electricity is a useful means of transforming energy

  give examples of ways in which energy can be stored

 

KS3 Physics: How does electricity transfer energy?

   how current behaves in electrical circuits

   Review pupils’ understanding of simple circuits – the requirements for current to flow, and the effect of the number of cells or components in series and parallel circuits (unit 7J ‘Electrical circuits’) – by using quiz cards that describe real circuits with faults and by measuring currents in circuits.

  describe current as not being used up in a circuit and as dividing along the different branches in a parallel circuit

  identify that an ammeter measures flow of current

 

 

   how to measure voltage in a circuit

   Ask pupils to construct simple series circuits incorporating several components and batteries or power supplies of different voltages. Help them to connect the voltmeter across each component in turn, without breaking the circuit. Individual readings can be seen to add to the total voltage. Encourage pupils to associate large voltage changes with large energy transfers by the components, eg bright bulbs.

 

  use a voltmeter correctly

  draw from trends in numerical data conclusions about the way voltage varies around a circuit

   Emphasise that ammeters measure flow ‘through’, so are inserted in a circuit; voltmeters measure a ‘difference’, so are connected across a circuit, without breaking it.

   a simple model of energy transfer from batteries to components in circuits

   a simple model of potential difference making a current flow in a circuit

   to work with others to simulate energy transfer around a circuit

   Introduce a model to associate energy transfer with voltage, eg the ‘almost Monopoly’ or ‘pocket money’ analogy, where pupils are given money that has to be spent around the circuit before they can return. Pupils are the current, the cell is the source of the money (‘GO’), which is the energy. The cells or voltage permit them to move. If they go through more cells, they pick up more money; and as they go round the circuit, they have to pay out equal amounts per device (assuming identical devices). As an analogy of resistance, money could be paid out in proportion to ‘number of hotels’, or use a similar rule from Monopoly. Note the shortcoming in the analogy – in Monopoly circuits all the money does not have to be spent.

   An alternative model is the ‘up-and-down’ ski-lift. Chairs are the ‘current/charge’ which the ‘voltage’ of the motor causes to move (flow). Skiers are the ‘energy’, climbing on at the motor-house and getting off at suitable places (‘devices’) around the ski-lift circuit.

  use a simple model to describe the link between voltage and energy in a circuit

  learn how to identify faults in equipment

  choose a suitable method for presenting results

   With some pupils, the term ‘potential difference’ could be substituted for ‘voltage’ and linked with other uses of the word ‘potential’.

   Other models use ideas of water pressure and gravitational potential energy. Encourage pupils to devise their own models to explain features of their observations, eg an energy carrier/supplier, continuity of circuit.

   A particle model of electricity is not required (electrons can be left until key stage 4), but the idea of static charge could be used here.

 

KS3 Physics: How does electricity transfer energy? (Cont.)

   that a cell has chemical energy, which is transformed to electrical energy in a circuit

   to consider which factors are important and how to vary them

   to choose appropriate techniques and equipment

   to explain results that do not fit a pattern that arises

   to compare their investigative method and results with those of others and evaluate the work in the light of comparisons

 

   Show the inside of a dry cell. Establish that there is a chemical change when a battery/cell produces a current. Associate the energy of the chemical change with input to a circuit.

   Ask pupils to plan an investigation into how to make a cell from a fruit or vegetable to produce the highest voltage, eg the performance of a particular fruit with a range of electrode sizes, separations or metal combinations, the relative effectiveness of different fruit. If appropriate, link to work on the relative reactivity of different metals.

  describe energy transformation from a cell/battery to a circuit

  identify and describe patterns in data

  draw conclusions from their data

  describe how to improve their work, eg by identifying strengths in the work of others

   Reactivity of metals is covered in unit 9F ‘Patterns of reactivity’.

Safety

a dry cell contains hazardous chemicals. The use of solutions such as vinegar or lemon juice provides a cheaper alternative to a range of fruits. The size of the voltage depends mainly on the difference in reactivity of the metals used as electrodes, eg the best will probably be copper and magnesium, giving about 1.5V

– pupils’ plans should be checked for health and safety before practical work begins

   to apply scientific knowledge to explain the use and occurrence of high voltages

   Use the Electricity Council video Electric graffiti, or other secondary sources, to identify the hazards of high voltages and associate these with the transfer of large amounts of energy, eg lightning, overhead and power lines on railway tracks.

  give a reasoned report associating the use/hazard of high voltage with energy transfer

 

 

KS3 Physics: What are we paying for when we use electricity?

   that electric current is conducted from ‘the mains’ to components in electrical circuits

   that energy is transmitted via electricity to an appliance, where it is converted to another form of energy

   that some appliances transfer more energy than others (in a given time)

   to identify the power rating of common household electrical devices

   to present advice based on scientific understanding as a coherent text

   Discuss the household mains supply at 230V and how appliances, eg television, computer, run from this, using pupils’ experiences. Show an electricity bill and ask pupils What are the units used? Remind them that current is not used, but energy is. Show (pictures of) a household electricity meter.

   Demonstrate the energy used by a range of electrical devices, eg for heating, lighting, (over a fixed period of time for comparison purposes) using a joulemeter/datalogger. Show how these comparisons relate to the power ratings on devices.

   Ask pupils if they think people are aware of these differences, eg Do parents talk about the waste of money of ‘leaving the TV on all evening’? Ask how they could find evidence to check such comments, and then devise a parents’ guide entitled ‘How to get your children to save energy by switching the right things off’. This could be supported by putting examples of household appliances on cards and asking pupils to arrange them in order of energy consumption. Compare the amount of energy used by a range of devices in the home or school, as shown by the power rating noted on the devices, eg light bulbs, fridges, microwaves, heaters, cookers, computers, televisions.

  give examples of some devices that use energy at a greater rate than others, eg heating appliances transfer more energy than others

  give an example of their own use of an electrical appliance that has to be paid for

  contribute to planning and carrying out a survey of energy use of household devices

  communicate data effectively through writing a coherent text

   This is best not done as a class experiment as the joulemeter may be confused with the ammeter. Here it is simply required to gather data for comparison purposes.

   The concept of power as rate of energy transformed could be introduced to some pupils. Here it is used to support the simple comparisons, eg heaters use a lot of energy, other devices less.

   Spreadsheets could help pupils make quantitative comparisons.

   Extension: some pupils could be told that the unit charged for is a kilowatt hour, and be asked to find out about the costs of using devices for typical times per day, eg TV for 6 hours, fridge for 24 hours. This could be compiled and presented as a bar chart.

Safety

mains appliances must have been tested using a portable appliance tester. Any brought from home must be carefully checked

KS3 Physics: Checking progress

   to review their understanding of energy and electricity

   Ask pupils to summarise ways in which electricity can transfer and transform energy to provide people with useful facilities – as a list or a concept map.

  relate use of electricity to energy supply in everyday situations/devices

   Use an internet search engine to look for information.

KS3 Physics: Where do we get electricity from?

   that electricity can be made to flow by causing movement in an electrical generator

   that fossil fuels, nuclear fuels and renewable energy sources can be used to drive electrical generators

   to follow instructions carefully to construct and/or test a generator

   that electrical energy cannot be stored

   Elicit ideas about where mains electricity comes from. Trace the story back to a power station.

   Demonstrate a bicycle dynamo or simple generator. Show how increasing (energy) input will increase (energy) output.

   Use a small motor as an electrical generator, or make one from a kit, and test its output using a sensitive meter. Possibly drive it using a windmill