Dr. Free-Ride's better half taught the younger Free-Ride offspring's kindergarten class about matter this week. It was a lesson that included a working definition, some hands-on explorations of the properties of different sorts of matter, and a little magic.
Working definition of matter (for kindergarteners): Something that has mass, takes up space, and that interacts with our senses. ("But what of electrons?" asked Dr. Free-Ride when hearing about the lesson. "Too soon!" replied Dr. Free-Ride's better half.)
- Air is matter. The kids inflated balloons (some with adult help) and noted that the air inflating the balloons took up space. Also, they could feel the air as they let it escape from the balloon. "Air is matter even though we can't see it!"
- Paper and clay are both matter, but they have different properties. The kids folded, crumpled, and cut some paper. Then they folded, smushed into a ball, and cut some clay. Actually, they were surprised and thrilled that they could cut clay (who knew?), and equally impressed with their discovery that, unlike cut paper, cut clay can be put back together again without the aid of cellophane tape.
Dr. Free-Ride's better half waved a paper towel over a filled tub of water and said to the kids, "I can lower this dry paper towel into the full tub of water and it won't get wet!" The kids, of course, were dubious.
Dr. Free-Ride's better half lightly crumpled the dry paper towel and stuffed it in the bottom half of a paper cup, then lowered the inverted paper cup straight downward, well below the water level in the tub. After some gasps and giggles, the cup was raised straight upwards and the dry paper towel was withdrawn with a flourish.
Of course, because this was science class, the kids got the explanation: the paper towel stayed dry because the air in the inverted paper cup kept the towel from coming in contact with the paper towel. They also got to see what happens when the paper cup diving-bell was tipped whil submerged: bubbles of air came up and the towel got wet.
Dr. Free-Ride's better half left the kids with something weird to ponder: light isn't matter, even though (some of) our senses are good at detecting it. Photons are massless.
It was a good lesson.
Too cool. Your better half did a good thing well!