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Experiment

Sink or Float Experiments

Bring 10 objects to the bath and predict which ones will float. Your success rate will surprise you.

Ages 2–815–30 min1–2 kidsHousehold items

Before bath, collect 10 household objects: a coin, a cork, a lemon, a grape, a small toy, a stone. Predict whether each will float or sink. Test them. Results are consistently surprising. A lemon floats, a grape sinks.

What you need

  • 10 household objects of varying density and shape

How to do it

  1. 1Bring ten objects here. Before each one goes in, guess: will it float or sink?
  2. 2Drop each one in. Record what was right and what was wrong.
  3. 3Sort into two groups at the edge of the bath: floaters and sinkers.
  4. 4Ask: what do the floaters have in common? Let them figure it out.

Variations

  • Korb-Tür: If they won't predict — just watch you drop objects. They can cheer for floaters or sinkers. Prediction is optional.
  • Ausstieg: Leave the floaters in the bath. 'They stay tonight. Tomorrow we'll test the sinkers.' Peel the lemon and test it again next time.

💡 Parent tip

The lemon always wins. It floats despite being dense fruit. Peel it and drop it again. It sinks. The skin traps air. That one fact produces good conversation.

What your child develops

  • Density intuitiondeveloping a feel for why some objects float before formal science
  • Hypothesis formationmaking a prediction before observation
  • Classificationgrouping observed results by shared property

Safety notes

  • Never leave children unattended in the bath.

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