If you microwave a large marshmallow for thirty seconds, it gets the size of a softball, is soft and gooey and shrinks as soon as you open the door. Makes a nice little sweet tooth snack it you're into marshmallows--which I am currently. Microwaving it for thirty-five seconds makes some of the sugar caramelize on the plate that you had better have put it on first, and then when you open the door and it starts to shrink and cool, it also hardens like concrete on the plate. You can only get it off by letting it soak in water. I'm going to try thirty-two seconds next!
Marbles are very handy for science experiments, especially when you are trying to teach Newton's three laws of motion. I made some ramps out of some one-inch wide curved trim to run marbles down. If you set the two ramps up facing each other, you can get some really nice illustrations of "for every action there is an equal and opposite reaction."
Marshmallows are great for science, too. I used big and little ones together with toothpicks to makes models of water molecules. Then it's easier to explain chemical bonds, hydrogen bonds and why the heck ice floats. And when the explanation is over you eat your demonstration.
I'm very happy at the moment. Today I taught three sciences classes and a logic class. They all went well. The balloon rocket rocked, the tennis ball really pinged the ping-pong ball, and the marbles stayed on track. Now I am on a teaching break for one full week. It's enough of an excuse to microwave another marshmallow to celebrate.