100 Days of Science #85-- Sink or Float?

Through the years we've tried many different sink or float experiments and we have rarely been wrong.  I thought it might be fun to try and see if we could sink an orange and then get it to float again.

First I asked the boys what they thought would happen if we placed an orange in a bowl of water.  Two of the boys thought it would float but one argued that there isn't much air inside an orange so it would probably sink.

We filled a very large bowl up with water and stuck the orange in.  It almost sunk but it slowly lifted up from the bottom of the bowl just a bit and we could see it bobbing along just barely breaking the surface so it did indeed float.

We talked about why such a heavy object can float (like boats) and hypothesized about what we could do to make it sink.   We decided to peel the orange and it sunk completely right away!

I challenged the boys to think of what they could do to make the orange float again.

I got a few suggestions that we thought might have worked. Sadly taping the ends shut wouldn't work because the orange was wet and tape wouldn't stick to it.  We also didn't have a board to put under the orange... as one of the boys suggested making a raft.  But we did try putting our orange in a plastic bag and zipped it shut.  It floated so high in the water and we talked about why the air inside the bag offset the weight of the orange so much better than just the peel alone.

It was a great problem solving challenge and just 15 minutes later we were all done with science for the day.

Others in this series:
58.  Exploding Snow and Water Baggies 
59.  Exploring Properties of Minerals
60.  Visiting the Hartford Science Museum
61- 63.  3 Difference Bridge Challenges
64.  Making Models of the Earth's Layers 
65.  Graham Cracker Plate Tectonics 
66.  Homemade Lava Lamps
67.  Movies We're Watching for Science
68.  Index Card Tower Challenge 
69.  Learning Botany at the Botanical Gardens
70.  Board Games for Science
71.  Homemade Frozen Yogurt Pops
72.  Starburst Rock Cycle 
73.  & 74.  Making Marshmallows Sink and Grow
75. Jumping Conversation Hearts
76-78.  Making Paper Airplanes 3 Different Ways 
79.  Learning About Hummingbirds
80.  Planting an Herb Garden
81.  Mushroom Spores
82.-84.  Penny Saturation Experiment


  1. I always enjoy reading about the extension activities you include with your experiments. You really push your kids to think and to be creative!

    1. Thank you! I do try to get them thinking critically and creatively as often as possible.

  2. Thank you for sharing at #ThursdayFavoriteThings. Pinned and shared


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