Sink or Float Kitchen Lab
Test ten safe household objects in a bowl of water, make predictions and record which ones sink or float.
By WonderCraft Kids Editorial Team, Editorial team · Updated 6 August 2026
This is the first proper experiment most children run. Pick objects, guess, test, record. The surprises — a heavy candle floating, a tiny paperclip sinking — are what make the idea of density stick.
What you need
- A clear bowl or tub of water
- 10 safe household objects: cork, spoon, coin, lego, orange, sponge, key, crayon, leaf, candle
- Paper and pencil for the chart
- A towel
Step by step
- 1
Line the objects up and draw a two-column chart: sink, float.
- 2
Hold each object up and ask for a prediction before it goes near the water.
- 3
Write their guess in the right column, even when you know it is wrong.
- 4
Test it, then mark whether the guess was right.
- 5
Discuss the surprises — an orange floats, a peeled orange sinks. Try it.
- 6
Count how many they got right and run a second round with new objects.
What kids learn
Prediction and testing
Committing to a guess before testing is what separates an experiment from splashing.
Density, intuitively
Heavy-for-its-size sinks. They will not use the word, but they will grasp the idea.
Recording data
Their first data table. Seeing results accumulate on paper is a powerful thing.
Make it easier
Five obvious objects, no chart, just a sink pile and a float pile on the towel.
Make it more challenging
Introduce boats: can they make a sinking object float by changing its shape in foil?
Safety and supervision
- Supervise all water play; use a shallow bowl for younger children.
- No sharp or breakable objects, and dry everything electrical-adjacent immediately.
- Mop up splashes as you go — wet kitchen floors are slippery.
Adult supervision is required for every activity on this site. Read our full child safety guidelines.
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wondercraftkids.com
Sink or Float Kitchen Lab
Ages 3-6 · 20 min · first real experiment
Ages 3–6 · Low mess
Suggested pin description
Sink or Float Kitchen Lab: Test ten safe household objects in a bowl of water, make predictions and record which ones sink or float. Ages 3–6, 25 minutes total, low mess. Full step-by-step instructions and a materials list at WonderCraft Kids.
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Frequently asked questions
Why does a heavy boat float?+
Because of the water it pushes aside. A flat foil sheet floats; the same foil in a ball sinks. Show them.
How do I extend this?+
Add salt to the water until an egg floats. The same object behaving differently is genuinely surprising.
