Key Stage 1 design and technology · Technical knowledge

KS1 wheels and axles: a guide for parents

In Years 1 and 2, children explore mechanisms, which are the moving parts that make a product work, and use them in things they make. Wheels and axles are one of the examples the curriculum gives, and a favourite with teachers because a rolling model is easy to build and easy to test. Along the way, children also find out how to make a structure, such as the body of a vehicle, stronger, stiffer and more stable.

Wheels and axles, explained

A mechanism is a set of parts that work together to produce a movement. The programme of study says that when designing and making, Key Stage 1 pupils should explore and use mechanisms in their products, and it gives levers, sliders, and wheels and axles as examples. Those are examples that schools may choose from rather than a required list, so your child’s class might have spent the term on wheels and axles, on levers and sliders, or on a mix of all three.

An axle is a rod that runs through the middle of a wheel. Either the wheel turns on the axle, or the wheel and axle turn together. This lets something heavy roll along instead of being dragged, which takes far less effort. In classroom models there are two common arrangements. In the first, the wheels are fixed firmly to the axle and the axle spins inside a holder, often a drinking straw taped to the underside of the vehicle. In the second, the axle is fixed to the body and the wheel spins freely on it. Either way, something has to be able to turn, and something has to stay still.

Before making anything, children explore. They look at real things that roll, such as pushchairs, trolleys, wheelbarrows and toy cars, and ask which parts turn and which stay put. They push and pull models and compare them, and they learn words such as wheel, axle, rotate and chassis. Then they follow the same steps as all design and technology: say who the product is for, draw a design, choose materials, make it, test it and say what they would change.

The second objective is about structures. Children are taught to build structures and explore how to make them stronger, stiffer and more stable. A vehicle body made from one flat piece of card bends easily, so they try folding up the edges, rolling card into tubes, gluing layers together or adding diagonal strips. These make the card stiffer. A structure is stable when it is hard to knock over, and children find that a wide base and a weight kept low make a model steadier. The mechanism and the structure work as a pair: a wobbly body makes the wheels run crooked.

Later in primary school, children meet more complicated mechanical systems such as gears, pulleys and cams. The ideas from Years 1 and 2 are the foundation: that movement can be changed or guided by a mechanism, that parts need to line up, and that testing shows what to improve. At this age the aim is not perfect engineering. It is for children to try, notice what happens and talk about why.

Words your child will hear

Mechanism: A set of moving parts that work together to make something move in a useful way.
Wheel: A round part that turns around its middle so that something can roll.
Axle: The rod through the centre of a wheel that the wheel (or the rod itself) turns on.
Axle holder: The part, such as a straw or a tube, that holds the axle in place under the vehicle while letting it turn.
Chassis: The base or frame of a vehicle that the wheels and everything else are attached to.
Stiff: Not easily bent. A rolled tube of card is stiffer than a flat sheet of the same card.
Stable: Steady and hard to tip or knock over, usually because it has a wide base.

What the National Curriculum says

The programme of study for Key Stage 1 says:

When designing and making, pupils should be taught to explore and use mechanisms [for example, levers, sliders, wheels and axles] in their products
When designing and making, pupils should be taught to build structures, exploring how they can be made stronger, stiffer and more stable

Objectives from the National Curriculum in England, © Crown copyright, used under the Open Government Licence v3.0.

Try it: making a car that rolls straight

A child is asked to make a model car from card, straws, wooden rods and wheels, and to test that it rolls straight down a gentle slope. An adult does any cutting that needs a sharp tool. Here is a typical sequence.

Make a stiff chassis. A flat rectangle of thin card bends in the middle, so fold up the two long edges to make low walls. The folds make the card much stiffer than it was.
Fix the axle holders. Tape two straws across the underneath, one near each end. They must be at right angles to the long edges and parallel to each other, so check from above with a ruler laid alongside each one.
Push a rod through each straw. The rods should be longer than the straws so that an end sticks out on each side. Spin each rod with a finger to check it turns freely.
Fix the wheels. Push a wheel on to each end of each rod, so that it grips the rod tightly, and leave a small gap between the wheel and the straw so that nothing rubs. The hole must be at the centre of each wheel. To find the centre of a home-made card wheel, cut a paper circle the same size, fold it in half and in half again, and the creases cross in the middle. Lay it on the card wheel and mark the centre through it.
Test it. Let the car go down a gentle slope, such as a tray tilted on a book. If it veers to one side, look at the axle holders first: they are probably not parallel. Straighten them, test again, and change one thing at a time.
Test the structure. Put a small toy on the car. If it tips or the card sags, make the body wider, fold in more stiffening, or keep the load low and in the middle.

The car rolls straight when the two axle holders are parallel, the wheels are the same size and fixed at their centres, and the rods turn freely. It carries a load without tipping when the folded card body is stiff and wide and the load is kept low.

Common mistakes and how to help

Fixing the wheels straight on to the body of the vehicle

Gluing parts on is how children attach most things, so they stick the wheel to the card. But a wheel that cannot turn just drags.

What helps: Ask, “What has to turn?” Let your child spin a real wheel and find the rod it turns on. Then look for something that holds the rod but lets it spin, such as a straw.

Thinking any round shape will roll well

A circle cut by eye is rarely perfect, and a hole made off centre makes the wheel bump up and down as it turns.

What helps: Find the centre by folding a paper copy of the circle in half and in half again. Roll a wheel with a centred hole and one with a hole off to the side, and talk about the difference in the ride.

Using “strong” and “stiff” to mean the same thing

In everyday talk, a tough thing is both. But a strip of card might not snap and still bend a lot, and a sheet of glass is very stiff but can shatter.

What helps: Use the words precisely. Strong means it doesn’t break, stiff means it doesn’t bend, and the two can be tested separately by pressing on the middle of a card bridge.

Making a tall vehicle with a heavy load on top and expecting it to stay upright

Children often build up to make something impressive, without noticing that height and a high load make a structure tip more easily.

What helps: Tilt a box with a toy on the top and again with the toy at the bottom. See which one tips first, and then widen the base and lower the load.

How to help at home

Wheel and axle hunt. Look around the house and on a walk with an adult for things with wheels: a pushchair, a suitcase, a chair, a scooter. Ask your child to point to the axle and to say what turns and what stays still.
Build a cardboard car. Use a small box or a folded strip of card for the body, drinking straws as axle holders and blunt-ended craft rods for axles. Wheels can be card circles or bottle tops. An adult should make any holes and trim the rods.
Ramp testing. Tilt a tray or a board on some books and let different vehicles roll down. Ask which went furthest and which went straight, and change one thing at a time, such as the wheel size or the load.
Make paper stiffer. Bridge a sheet of paper between two piles of books and see how many coins it holds. Then fold it into a concertina or roll it into a tube and try again. Children enjoy seeing the same paper become much stiffer.

Leads on to

Key Stage 2: Strengthening and reinforcing structures
Key Stage 2: Gears and pulleys
Key Stage 2: Cams, levers and linkages
Key Stage 2: Series circuits in products
Key Stage 2: Programming and controlling products