Explore the densities of various objects using bubbly soda water and a few clear glasses on the Light Cube!

Pour a bit of club soda into a clear glass. In the second glass, pour some water. The carbonated fizz or bubbles in the soda will start to lift and dance around inside of the glass. Ask students to consider why the carbon rises up and out of the glass.

We asked our friend Malak to observe the bubbly fizz and the glass of water and try and guess what will happen if she dropped a toothpick into each glass. She guessed that the toothpick would sink in the glass with water, and rise in the glass with soda.

As you can see, the toothpick floats midway up the glass of water. Interesting! Why is this so? Malak asked if this had something to do with the wood of the toothpick… perhaps it floats like a log in water? We moved on to test her hypothesis of whether or not the toothpick would float in the glass with soda.

This time we dropped the toothpick into the glass of soda and observed that it proceeded to float just like the toothpick in water.

We tried the hypothesizing and experimenting again with other found items such as buttons, beads and erasers.

Ooh! Now we have a surprise. We guessed that the Fancy Stringing Ring we dropped into the glass with water would float. It floated when we dropped it into the glass with soda. But why did it sink to the bottom? These are great questions to be asking your students as you develop new theories on why some items float why others do not.

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