Our Swimming Creatures of the Sixth Day curriculum kicks off with information about the ocean itself, and one of the neat activities demonstrates how water temperature affects water movement.  Thermohaline currents are deep ocean currents, caused by temperature, or salt content or both.  In this experiment we were only working with water temperature.

Our question:  Which is heavier – hot or cold water? Grace decided that hot water was heavier.

The procedure is as follows:  First put a few drops of blue food coloring in a clear container of hot water.  Then put a few drops of yellow, in a cup of ice water.  Pierce the cup, and observe the yellow ice water, as it escapes into the blue hot water. 

Then we did the experiment in reverse:  This time put the blue food coloring in a clear container of ice water.  Then put a few drops of yellow in a cup of hot water.  Pierce the cup, and observe the warm yellow water, as it escapes into the cold blue water.

We observed that the yellow cold water leaked toward the bottom, and then mixed.  We also observed that the blue food coloring blended really quickly in the hot water.  We then observed that the hot yellow water when it leaked moved upward.  Grace decided after watching this that “Really, I have to say that cold water is heavier than hot water. ”  

Here are a few photos, followed by our conclusion!

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She didn’t like the idea that her hypothesis was proven wrong, but I explained to her that this is actually how science is supposed to work!  If you ignore your results, or try to skew the results to prove your hypothesis, you might be considered a global warming expert!