Sink or Float Guess

What you need

• a washing-up bowl of water
• a tray of things to test, like a spoon, an apple, a sponge and a toy brick
• a cloth for drips

How to do it

1. Set the bowl of water on the floor, with the tray of things beside it.
2. Hold each one up and ask "Will it sink or float? Why do you think so?"
3. Let them drop it in and watch what happens.
4. Sort everything into two piles afterwards: the floaters and the sinkers.

Why it matters

Guessing first and then finding out is how a scientist works, and asking why gives them a reason to explain.

What they're learning

Guessing and testing

Saying what they think will happen, then seeing if they were right.

Giving a reason

"Because it's heavy" is a first go at explaining.

Sorting

Two piles, floaters and sinkers, from what they saw.

What to look for

Notice them changing their guess after a surprise, like a big apple floating.

A tip

Put a cloth under the bowl for splashes, only test things too big to fit through a toilet roll tube, stay beside them the whole time the water is out, and tip it away as soon as you finish.

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