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Floating Stone Float or Sink Experiment

May 18, 201418,804 views
Science
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by TurkeyMom in Science

Ages3–7 yrs
Prep15 min
Activity20 min
Leveleasy
MessMedium
Works for1:1 · Small group · Class

Kids predict whether everyday objects will float or sink, test them in a tub of water, and then meet a surprise: a pumice 'stone' that floats. Finish by sorting everything into labeled Float and Sink jars.

⚠️ Safety first

  • Small test objects (popcorn, raisins, pebbles, gravel, pom poms, bell) are choking hazards. Supervise closely, and leave them out for kids who still put things in their mouths.
  • Popcorn and raisins are test objects here, not a snack. Don't eat them after they've been in the water.
  • Always supervise children around a container of water, even a shallow one.
  • The post uses glass jars for sorting. Glass can break, so an adult should handle them or use clear plastic jars.
  • Wipe up splashes so no one slips.

Before the kids arrive

  • Label two jars 'Float' and 'Sink'.
  • Gather leaves, twigs, stones and pebbles from outside.
  • Optional: print a sink or float record sheet for each child.

Steps

  1. Fill a simple round container with water.

  2. Set out the test materials: pom poms, leaves, twigs, stones, pebbles, gravel, popcorn, raisins, a bell and feathers.

  3. Pick one object and guess: will it float or sink?

  4. Drop it in the water and check whether your guess was right.

  5. Keep guessing and testing until every object has had a turn.

  6. Feel the pumice 'stone' and predict what it will do, just like the other stones.

  7. Put the pumice stone in the water and watch it float.

  8. Try pushing the stone to the bottom and watch it come back up.

  9. Look closely: most of the stone is under the water, and only the top sits above the surface.

  10. Sort the materials into the 'Float' and 'Sink' jars and keep watching them.

Tips

  • We used a wide variety of materials to see the contrast.from the author
  • The popcorn was their favorite.from the author
  • Hold the pumice back until the end. The word 'stone' sets kids' minds on 'sink', especially after the other stones and pebbles have gone straight to the bottom, so it feels like a magic stone when it floats.from the author
  • Why it floats: pumice is a highly porous material made of volcanic ash. Its air cavities make it really light. Left in the water for a long time, water fills the cavities and it eventually sinks.from the author
  • We didn't use an observation sheet, but a simple printable (the author likes Buggy and Buddy's) lets kids record their predictions and results.from the author
  • Repeat the experiment later with new materials to see what the kids remember about the different variables.from readers

Make it your own

  • Leave the pumice stone in the water for a long time and check back to see when it finally sinks.
  • Use a sink or float printable to record predictions and results.
  • Repeat later with a new set of materials to see what kids remember.

The story behind it

By TurkeyMom · May 2014
materials
We used a wide variety of materials to see the contrast. I used a simple round container, filled it up with water and set out the materials pictured above.
1 / 7

Floating Stone Float or Sink Experiment: the original post

Set up the classic float or sink science experiment with a twist When they are not being tested, I guess every single child loves science and loves experiments. Their innate curiosity is being nurtured when they are given the freedom to observe, experiment and predict.With this classic float or sink science experiments kids love to experiment the concept with utmost joy. Today’s float or sink science experiment has a small twist though. I included a new material! Materials We used:

  • Pumice Stone
  • Pom Poms
  • Leaves
  • Twigs
  • Stones
  • Pebbles
  • Popcorn
  • Bell
  • Raisins
  • Feathers
  • Gravel

We used a wide variety of materials to see the contrast. materials I used a simple round container and filled it up with water and set out the materials pictured above. We really did not use a observations sheet or any printable. I love this simple printable by Buggy and Buddy! kids experiments with science The kids enjoyed first guessing whether the object will float or sink and immediately compared their predictions with the actual results. The popcorn was their favorite. sink float science experiments Then I introduced this fun material. A bath pumice “stone”. The word “stone” kind of set their mind with the “sink” answer. Both the kids felt it and decided that the “stone” will sink just like the other stones and pebbles that went straight to the bottom of the container. Science for kids Here is the product link for the “stone” But to their surprise this “stone” floats. Yes, it floats for a long time and the kids tried pushing them down to the bottom but it would come back up. However if you observe a large part of the stone is submerged in the water while the top part still is above the surface of the water. But to kids this “magic” stone is floating. kids science experiments The pumice stone is a highly porous materials made of volcanic ash. The presence of air cavities makes it really light and it floats for a while. Leaving the stone in the water for a long duration makes the water enter the cavities and it does eventually sink to the bottom. Science Experiments for Kids : Floating Stone experiment Later I set out 2 jars with labels on them and the kids sorted the materials into the jar for extended observation. float sink experiments for kids

Thanks for reading

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What readers say

💬 1 comments

🎉 Worked for us

Redo it to check what stuck

A parent had already run a quick version with her boys to teach variables, and plans to repeat it with these materials to see what they remembered.

“I did this experiment quickly with my boys to teach them about the different variables”
PinkOddy, May 2014

Tried it?

Reviewed before it appears. No links, and please no children's names.

Read all 1 comments

  1. PinkOddy · May 2014

    I did this experiment quickly with my boys to teach them about the different variables - I might just do it again with some of your materials and see what they remembered. Thanks for sharing.

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