This event started with thinking about the previous event I did with the girls on the limitations of our sensation of heat and temperature differences with 3 bowls of water, hot, warm and cold. In that version you can get disparate sensations from the warm bowl from hands that had previously been in the other two bowls one feeling cold/colder and the other feeling it as hot/hotter. I wanted to explore one of the other common misinterpretations from our sense of touch about temperature, in particular insulators and conductors of heat.
Materials
Insulated cutting board (same temp as the counter)
Granite counter top (same temp as the board)
IR thermometer
2 Ice Cubes
Notes
First part was to have the girls feel both surfaces and make observations on how each feels and make estimates on relative temperatures. Once they've done that we used the IR thermometer to confirm that they were nearly identical temperature and discuss further. They both had observed that the counter felt cooler than the cutting board and when they discovered the truth didn't quite understand why their fingers were deceiving them.
The second part was to go in another direction to illustrate other ramifications of the disparate heat transfer rates of the materials. To do this I got two fresh ice cubes from the freezer and asked them (with them knowing that they were the same temperature and that the counter felt cooler). They both took the bait and guessed that the warmer feeling (and slightly warmer actual temperature) cutting board would melt the ice faster. It was obvious right away how the counter was melting the counter far faster and after 3 minutes the counter cube was all gone and the other was barely changed. At this point we talked about material differences of insulators they knew about like Styrofoam coolers and travel coffee mugs versus things like stone and metal pans.
After thoughts include having them explain what we did to their mother and revisiting what we learned about limitations of our sense of touch and noting temperature differences. Bringing up how much of a difference there is between thermal conductivity of air vs water and how that affects how cold air vs cold rain feel (and the ice demonstration was a way to reinforce that it's not just a sensory trick or limitation of our skin like with the water bowls).
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| The fancy materials for this demonstration. |
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| Initial observations |
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| Phase two begins and Lana notices rapid melting on the counter. |
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| After 1 minute the granite cube is diminishing rapidly. |
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| The insulated board cube is hardly changed and the granite cube is completely gone. |
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