Hopping Corn and Cranberries

Just in time for Thanksgiving, I’ve got a fun quickie experiment to do with your cranberries and some popcorn kernels.  If you’ve tried my Dancing Raisins experiment, then this will be familiar.

Here’s what you’ll need to get started:

  • Dried Cranberries
  • Popcorn kernels
  • Soda water, Ginger Ale, Sprite, Club Soda, sparkling water or whatever clear bubbly (kid-friendly!) you have at home
  • clear jars or cups

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I asked the tots to touch the dried cranberries and the popcorn kernels and describe how each felt.

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For younger tots, I prompted them with simple questions such as:

  • Is it soft or hard?
  • Is it smooth or bumpy?
  • Is it sticky or slimy?

Fill one cup with water and one cup with soda (we used diet Ginger Ale because that’s what we have at home), but any clear bubbly soda should work fine.

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We also compared the difference between the soda and the water.  They immediately noted the difference in color and the presence of bubbles in the soda.

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Next, I asked them what they thought would happen if the cranberries were added to the water? They all thought they would sink to the bottom.  After making their predictions, they added the cranberries to test their theories.

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Yes, the cranberries sunk to the bottom.

I then asked them what they thought would happen if the cranberries were put in the soda.  They again thought that they would sink.

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So they did sink… at first.  But then they “hopped” to the surface… and then dropped again… and rose again.

We repeated the same steps with the popcorn kernels.  When we added the popcorn kernels to the water, they sank as well.

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Then we added them to the Ginger Ale.  And discovered that the popcorn kernels did the same thing!

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It was mesmerizing to watch them “hop” up and down.

We will definitely be trying this again with several other sodas and sparkling water!  You can also make a bubbly solution with vinegar and baking soda as well.

Another extension/variation of this experiment is to try out different items, other than cranberries that might behave in a similar way, such as raisins, dried macaroni, etc…  Search your pantry.  The options are endless.  Happy Hopping!

Also, try my Dancing Raisins experiment for a different twist to a similar activity!

The Science behind the Activity:

This is a great experiment demonstrating sinking and floating.  Cranberries are denser than the liquid so they initially sink when you put them in.  As the carbon dioxide gas bubbles attach to the surface of the cranberries, they decrease the density of the cranberry and the cranberry floats to the top (dances and shimmies its way to the top!) At the surface of the liquid, the gas bubbles pop and the cranberry sinks back down.  The process keeps repeating until there isn’t enough carbon dioxide left to raise the cranberries.  The same holds true for the popcorn kernels.