# Do Pumpkins Sink or Float?

Sink or float is a classic preschool activity.  You gather an assortment of items and have the children guess which will sink or float, and then test their hypotheses.  (It made me laugh not too long ago when David Letterman added a gag segment called “Will it Float” with a huge pool of water and random items for the members of the audience to make predictions about.  I’m guessing he’d been to his little boy’s preschool the day he came up with that one!)

This fall, consider adding pumpkins to your list of items to test.  What do YOU think?  Sink or float?  You may need a larger bin  for testing pumpkins (I’ve used a bath tub in the past), but it will be well worth it.  You may want to just add a pumpkin to the list of other items you usually test, or you may want to do an exclusive pumpkin test.

Gather a variety of sizes of pumpkins.  Talk with the children about which is the biggest, smallest, etc. and even line them up in order (great math work here).  Then have the children share their hypotheses about each pumpkin.  Will it sink or float?  Why do they think that way?

Are you still wondering if they float?  They do!  In fact, I once used a huge, 25 pound pumpkin, and it still floated!  (They don’t float on top of the water, obviously, but they bob with about 1/3-1/2 of the pumpkin above water.)

Many children will think that your mini pumpkin will float, but that the huge pumpkin they can’t even lift will not.  Talk – very briefly- about density.  Density is what makes something sink or float, not weight.  It’s about how the weight is spread out.  Sometimes I even make the connection between balloons and pumpkins, floating both in the water for the visual effect.  They are both made up mostly of air on the inside.  Having more empty spaces makes something less dense and that makes it easier to float.

Now I certainly don’t expect each child to come away knowing that an object must have a density of less than 1 gram per cubic centimeter in order to float.  But I think it doesn’t hurt to expose them to the vocabulary and concepts, to get them thinking and applying in future situations.  This activity obviously builds science  knowledge, but perhaps more importantly than building specific knowledge about floating and density, is that it gives the children experience with the scientific method.  As they ask questions, make hypotheses, test their hypotheses, and discuss their findings, they’re learning how to learn!  And that’s a skill that always keeps kids on top!