Three containers of very different shapes come to the bath. The child fills one and pours it into the next, then is asked: is there more or less water now? The amount stays the same but never looks the same. Children who figure this out through their own repeated testing hold it differently than children who are told.
What you need
- 3 containers of different shapes but similar volumes
How to do it
- 1These three containers look different. Do they hold the same amount of water?
- 2Fill the tall bottle to the brim. Pour it into the short wide pot. More or less?
- 3Pour it back. Ask again. Repeat between all three containers.
- 4It always looks like a different amount. That is what makes it a laboratory.
Variations
- Korb-Tür: If they won't pour — you pour and they predict. They watch the transformation. Pouring is optional.
- Ausstieg: One final pour from tall to wide. Let it settle. 'Same water. Different shapes. That's the secret.'
💡 Parent tip
Don't explain conservation of volume beforehand. The experience of being wrong and then verifying is the learning. Explaining it first replaces the experience with a piece of information — less effective and far less memorable.
What your child develops
- Conservation of volume — the Piagetian concept that volume doesn't change when container shape changes; this is the bath-based version of that classical experiment
- Prediction and revision — forming, testing, and revising a belief is the foundation of empirical thinking
- Perceptual override — learning that perception (height = more) is systematically wrong is a lasting conceptual development
Safety notes
- Never leave children unattended in the bath.
More for “Calm down”
See allThe Invisible Journey
Close your eyes. You're traveling somewhere right now. Where do you go?
The Favorites Lists
Make 5 lists of your favorites. A different category for each list.
The Eyes-Closed Drawing
Draw something specific with your eyes closed. Open, look at the disaster, laugh, try again.