Spontaneous Science

I got on the phone, I thought briefly, with a mom whose husband is going to do a free homeschool science class for 8-11-year-olds, only a mile down the street. I had seen the post about it, emailed Jeff to see if it was religious-based science, and he emailed me back asking me to call. It's not religious-based (they're Jews, it turns out, not fundies), and that's all I really needed to know, but his wife Leslie talked and talked and TALKED. In between various subjects, she turned me on to science experiments from Steve Spangler:
http://www.stevespanglerscience.com/experiments/

She said that they had recently done the Ivory soap experiment, so while she was talking at me about something, I brought up that experiment on the computer (yes, I know, Bad Deb), and saw that all it involved was a bar of Ivory soap and a microwave. The girls kept looking at me with those when-are-you-going-to-get-off-the-phone-we're-tired-of-being-patient eyes, and so I went upstairs and got a bar of Ivory soap, summoned the girls, and (with a few "ohs" and "rights" to Leslie, still chattering away) put it in the microwave on High for 2 minutes. Wow, it was really cool.

Here is the experiment: http://www.stevespanglerscience.com/experiment/00000053

If you do it, make sure you watch the whole process, don't leave. We had to turn it off with 30 seconds to go, because I think our microwave is extra-powerful.

When I got off the phone we were able to discuss the history of Ivory soap and how it came to float, then talked about floating in general, then about melting and boiling points, and then it turned into a states of matter discussion.

So, for kicks, we took an ice cube and put it in a cold pot on the stove and watched it melt on high power. We timed how long it took to melt (1:28), and then to boil away completely (2:22). We then tried it again with an ice cube in an already hot pot, and found it melted and vaporized much more quickly. We talked about heat transfer, and why it melts much more quickly in a pot that is already hot. Then I had Ella hold an ice cube in her hand and time how long it took to melt (7:10).

When I asked the girls how long it would take before it boiled in Ella's hand, Madison didn't really think it through and blurted out "About an hour!" but Ella took a few moments more and said "Never. My hand isn't hot enough to make it boil." And then Madison protested that water does evaporate, and we talked about the difference between the process of evaporation and boiling.

"Why must the water cycle be driven by evaporation, and not by boiling?" I asked. For the same reason that Ella's hand could never make it boil -- if it was hot enough on earth to boil water, the earth would be a very different place.

Of course, the child who loves arguments driven by nitpicking objected. "What about in the center of the earth? It's hot enough to boil water in there." We looked up the temperature in the inner core (7000 degrees C) and the temperature in the mantle (879 degrees C). Water would boil in there, yep. "Well how FAST would an ice cube vaporize in the mantle?" A fraction of a second. "It would be even faster in the core, right?" Yes. "How much faster?" I couldn't do any better than a fraction of a fraction of a second, which is of course unsatisfying.