Floating and Sinking

What is floating?

When something floats, it stays on top of the water. It does not go down.

A rubber duck floats. A leaf floats. A toy boat floats. They sit on top, like resting on a soft bed of water.

What is sinking?

When something sinks, it drops down to the bottom of the water.

A rock sinks. A coin sinks. A spoon sinks. They go down, down, down until they touch the bottom.

Why do things float or sink?

The water pushes up on everything you put in it. This is a kind of force, like the pushes and pulls you make with your hands.

• Things that are light for their size often float.
• Things that are full of air, like a ball, often float.
• Things that are heavy and solid often sink.

Shape matters too! A flat ball of clay sinks. But if you make the clay into a bowl shape, it can float, because it holds air inside.

Float and sink all around you

• A boat floats on a lake.
• A stone sinks in a pond.
• Bubbles float up in your bath.
• Your wet sponge can do both!

Try it yourself! 🛁

Ask a grown-up to help. You will need a big bowl of water and some small toys.

1. Find a few safe things: a cork, a coin, a plastic spoon, a small ball, a paperclip.
2. Guess first! Will it float or sink?
3. Drop each one gently into the water and watch.
4. Make two piles: a float pile and a sink pile.

Were your guesses right? Try a ball of foil, then flatten it into a boat. Does it change?

Stay safe: Always have a grown-up near water, and never put your face in the bowl.