Last week, we had a set of science demonstrations. Before we began, we talked about how they weren't experiments, because we knew what was going to happen, and we weren't really experimenting with any variables.
One demonstration showed us the effects of humidity by breathing on a plate of salt. We learned how salt can be used as a hygrometer, as the more water vapor is in the air, the more sticky and clumpy the salt becomes. Halfway through the demonstration, one group suggested trying the same demonstration with sugar. We used hot cocoa mix as a substitute, but the results were quite similar and actually was a more visible change in the mix due to the water vapor in our breath.
Another table had almost a microcosm of the water cycle. A jar with hot water was covered with a top that had ice on top. The hot water evaporated, and the cool top (which simulated a cool atmosphere) caused the water vapor to condensate. Every group witnessed the water vapor turning into small water droplets. Several groups even saw the jar begin to precipitate as the water droplets grew larger.
The final table demonstrated the concept of air taking up space. A balloon was placed over a water bottle and placed in hot water, causing the balloon to expand, and then cool water, causing the balloon to deflate. Led by Shubhanjali, we talked about how heat causes the molecules to bounce around, making them take up more space. When cooled, the air contracts, causing it to take up less space.
The demonstrations provided a nice opportunity for the kids to see some of the weather concepts in action, particularly since we have devoted so much of our science time lately to the expert projects. Several students got ideas to incorporate into their expert projects from the demonstrations, which was an added benefit. I am working on getting some pictures posted from the day, so they should be up soon!
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