Wednesday, October 10, 2012

You Can Have My Compass and Straight Edge

when you pry them out of my cold, dead hands.

I apologize in advance that I'm going to get a little critical of people I don't know who are trying to do a good thing, and are probably very nice. This landed in my inbox today from someone who offhandedly described it as "cute" with no further commentary.



"How do we know something is true?" is a big, maybe The Big Question in Geometry. At least, in my course. I hope in yours, too. It's a big, bad, fun, important idea.

Don't get me wrong, the makers of this video did a very slick job with it. It is very, very well done. But I don't get the point of cutesy-ing up exposition on the topic. When is a learner supposed to watch it? Before or after they have looked at a bunch of examples of something and made a conjecture and paused to wonder if that thing always has to be true, and just how they can go about knowing that? Before or after they encounter a surprising consequence of a ho-hum construction? I really, really hope this isn't any learner's introduction to what proof is for. They need to get their brains in the weeds of puzzles they can't leave alone. They need to get their hands dirty. Please, teachers of Geometry. I am begging you, here.

I suppose maybe I'd show it after. Like, way after. Months from now. It is pretty cute. Maybe it will help snap into place some ideas they will have knocking around in their heads. But my prediction is it will not hold their attention.