Year 3 science · Key Stage 2 · Forces and magnets
Year 3 forces and magnets: friction, poles and magnetic materials
In Year 3, children compare how things move on different surfaces, learn that most forces need contact but magnetic forces can act across a gap, and explore what magnets do. They sort materials into magnetic and non-magnetic, learn that magnets have two poles, and predict whether two magnets will attract or repel each other.
Forces, friction and magnets, explained
A force is a push or a pull. Children meet many everyday forces: opening a door, pushing a swing, kicking a ball, pulling a drawer open. Most of these need contact between two objects. Friction is a contact force that happens when two surfaces rub against each other, and it slows moving things down. Children compare how a toy car, a block or a ball moves on different surfaces such as carpet, wood, tile and a rough mat. On a rough surface there is more friction, so the object stops sooner; on a smooth surface there is less friction, so it goes further. Friction is useful as well as annoying: it lets shoes grip the ground and brakes slow a bike.
Magnetic forces are different because they can act at a distance. A magnet can pull a paper clip towards it across a gap without touching it, and can pull through paper, card, a table top or a thin layer of water. The force gets weaker the further away the magnet is. Children explore the shapes of magnets they might find in school or at home: bar, ring, button and horseshoe magnets, and talk about everyday uses such as cupboard catches, fridge magnets and the catches on bags.
Not every material is attracted to a magnet. Children test a range of everyday objects and group them as magnetic or not magnetic. They find that some metals, such as iron and steel, are magnetic, but many metals are not. Aluminium foil and copper pipes, for example, are not attracted. Wood, plastic, glass, paper and cloth are not magnetic either. Children should learn that “metal” and “magnetic” do not mean the same thing, and that some coins are magnetic and some are not, depending on what they are made of.
Magnets have two poles, called north and south, and the magnetic force is strongest at the poles. On a bar magnet they are at the two ends. If you bring two magnets together with unlike poles facing (north to south), they attract. If like poles face each other (north to north or south to south), they repel, pushing apart. Children use this rule to predict what will happen before they try, which is exactly what the curriculum asks for. They may also plan a fair way to compare magnet strength, such as counting how many paper clips a magnet can hold in a chain, or finding how far away it can pull a paper clip.
Words your child will hear
- Force
- A push or a pull.
- Friction
- A force between two surfaces rubbing together that slows movement down.
- Attract
- To pull towards. Unlike poles attract.
- Repel
- To push away. Like poles repel.
- Pole
- One of the two ends of a magnet, called north and south, where its force is strongest.
- Magnetic material
- A material that is attracted to a magnet, such as iron or steel.
- Non-contact force
- A force that works without touching, like the pull of a magnet.
What the National Curriculum says
In Year 3, pupils should be taught to:
- Compare how things move on different surfaces
- Notice that some forces need contact between 2 objects, but magnetic forces can act at a distance
- Observe how magnets attract or repel each other and attract some materials and not others
- Compare and group together a variety of everyday materials on the basis of whether they are attracted to a magnet, and identify some magnetic materials
- Describe magnets as having 2 poles
- Predict whether 2 magnets will attract or repel each other, depending on which poles are facing
Objectives from the National Curriculum in England, © Crown copyright, used under the Open Government Licence v3.0.
Try it: predicting and comparing magnets
Two bar magnets, A and B, have their poles marked. First: what will happen if the north pole of A is held near the north pole of B, and then near the south pole of B? Second: how could you fairly test which magnet is stronger?
- Remember the rule: like poles repel and unlike poles attract. North and north are like, so they should push apart. North and south are unlike, so they should pull together.
- Write the prediction with a reason. “North of A near north of B will repel because they are the same. North of A near south of B will attract because they are different.”
- Test the prediction. Hold the magnets close, a short distance apart, and feel the push or pull. Notice that the force is felt before they touch, which shows that magnetic forces work at a distance.
- To compare strength fairly, place a paper clip on a table. Slowly slide magnet A towards it, always with the same end, and measure the distance in centimetres at which the clip jumps. Repeat with magnet B. Keep the same paper clip, same table and same approach.
- Repeat each magnet three times, record in a table and compare. The magnet that makes the clip move from further away is the stronger one.
North to north repels and north to south attracts, because like poles repel and unlike poles attract. To compare strength fairly, change only the magnet, keep the paper clip, surface and starting point the same, and measure the distance at which the clip moves. The magnet that works from further away is stronger.
Common mistakes and how to help
Thinking magnets attract all metals
Children see magnets sticking to steel objects like cans and cutlery and generalise to all metal.
What helps: Test aluminium foil, a piece of copper wire or pipe, a plastic spoon and a steel spoon. Make a table of magnetic and non-magnetic metals, so they see that only some metals are magnetic.
Thinking that two magnets always attract each other
The word “magnetic” is linked with pulling things in, so a push comes as a surprise.
What helps: Let your child feel two magnets repel, and then turn one over. Mark the poles with sticky dots and test again, so the rule “like poles repel, unlike poles attract” comes from their own results.
Believing friction only happens on rough surfaces
We notice friction most on rough ground, so a smooth surface can seem to have none.
What helps: Every surface has some friction. A smooth surface has less, so things slide further. Compare carpet, wood and a smooth tile, and talk about the distances.
Thinking a magnet only works if it touches something
Most of the forces children use, like pushing and pulling, need touch.
What helps: Show a magnet moving a paper clip through a sheet of paper or card, or from a short distance. Magnetic force acts through the gap, but gets weaker as the gap grows.
How to help at home
- Surface race. Make a ramp from a tray propped on books. Roll a toy car down onto different surfaces, such as a rug, a wooden floor or a towel, and measure how far it goes each time. Which surface has the most friction?
- Magnetic or not? Gather ten safe objects, such as a spoon, foil, a paper clip, a coin (some are magnetic and some are not) and a pencil. Guess first, then test with a fridge magnet. Sort into two groups and discuss what the magnetic ones have in common.
- Pole detectives. Using two bar magnets with marked ends, find which ends attract and which repel. With an adult nearby, float one on a plastic lid in a shallow bowl of water and bring the other near; the lid will move towards or away from it without being touched.
- Kitchen sort. Use a magnet to test the food tins and cans in the cupboard, which are often steel. Do the same with the recycling and talk about how magnets can separate metals in a recycling plant. Be careful of sharp edges on cans.
- Magnet safety. Keep to the larger, ordinary magnets. Very small, strong magnets can be dangerous if swallowed, so keep them away from young children, and keep any magnets away from phones, tablets and bank cards.
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