Pumpkin Science: Sink or Float?

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This activity is just one part of the Young Explorers page featured in the Fall 2016 issue of Explore.

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Pumpkins can be pretty heavy. Do you think pumpkins float or sink in water?

Try it and find out!


  • Several pumpkins of different sizes
  • One jack o' lantern or carved pumpkin
  • Bathtub
  • Towels to keep the floor dry
MAS logo and owl carved pumpkins illustration


  1. Fill your bathtub with water.
  2. Gather a few pumpkins of various sizes and weights. For each pumpkin, make a prediction—will it float or sink?
  3. Gently place the pumpkins in the water and see what happens.
    • Was your prediction correct?
    • Why do you think the pumpkins floated or sank?
  4. Now try the experiment again with a jack o’ lantern or carved pumpkin. Make your prediction—will it float or sink?
    • Was your prediction correct?
    • Is this the same or different from what the whole pumpkins did? Why or why not?