Ages 4-7 · child and adult

Foil boat: cargo aboard

Make two shapes from matching pieces of foil. Watch what happens as you gradually add cargo.

Set your own pace. Preparation depends on your materials.

What to gather

Two 15 × 15 cm foil squares prepared by an adult
Shallow tray with a little water and a towel
Three matching large age-appropriate blocks, such as wooden blocks

Keeping it safe An adult stays beside the water throughout. No coins, small weights, tasting or sharp edges. Empty the tray immediately afterwards and dry the floor.

Choose a challenge level

Ages 4-5

Your child chooses a shape and adds one large block. The adult steadies the tray and helps shape the foil.

Ages 6-7

Try up to three identical large blocks in each shape. Record the count and watch the waterline. If neither sinks, compare how low they sit; do not add heavier loads.

Step-by-step instructions

The adult places a shallow tray securely on the floor. Shape two open foil bowls with rims above the water.
Predict which boat can carry cargo. Add blocks near the centre of the first boat, watching the rim approach the water.
Try the same blocks in the other boat. Stop if water enters. Try changing one shape or the way the cargo is arranged.

TATAAA

Now turn it into a game

Cargo rescue: the adult supervises a shallow water tray. Put the same light cargo in two boats and choose one for a paper harbour beside the tray.

When it gets tricky

Does the boat tip? Move the cargo towards the centre. A hole in the foil calls for fresh foil and a fresh test, not a judgement about your child.

When an experiment goes wrong

When you are done

Name one difference between the boats. Sinking ends the test; it is not losing.

If your child does not want to continue, it is fine to stop. You can safely swap roles or adapt the rules.

What to notice

Water exerts an upward buoyant force. The shape affects how much water the boat displaces before water spills over its rim. Cargo placement matters too.