A Greek letter, the Golden Ratio, and more dancing

Renata's Class:

Following the theme of logic, Renata had the kids playing a game to help them understand the idea of a "fair witness" - that is, one who can only speak things that are true. My main contribution to Renata's class this week was explaining why my tshirt was funny: the symbol in the cat's speech bubble is the Greek letter mu, pronounced "mew".

Susan's Class:

The Golden Ratio is a weird number sort of like pi. Its decimal expansion goes on forever without repeating, and it shows up everywhere. The Golden Ratio is approximately 1.62. It shows up in the proportions of the ideal body according to Leonardo DaVinci, in the Parthenon, and in the shape of credit cards. Sometimes people disagree on whether the Golden Ratio is part of something (such as the dimensions of the Great Pyramid, or the painting of the Mona Lisa).

We started with the idea of DaVinci's ideal dimensions. We paired the kids up and had them measure each other: first the distance from feet to bellybutton, then the distance from bellybutton to head. They divided the first distance by the second, and mostly got numbers between 1.5 and 1.8 - pretty close to the Golden Ratio!

I mentioned that credit cards are in the shape of a Golden Rectangle, and we started looking for other shapes with similar dimensions. The desks? The blackboard? A tissue box? Next time we need to measure other things besides the kids!

Elaine's Class:

More dancing today, with some jobs including the idea of "if and only if". I was impressed by Emi, who really got the idea that "if A then B" means "if A happens you have to do B, but you can also do B if A doesn't happen".