The Parallel Postulate and an unfortunate Pedagogical Shortcut
the text goofs, big, and two freshmen are able to do what the book says cannot be doneI teach very little Geometry. It is my least favorite high school course*. But I am teaching Geometry this term. Two sections. Advanced freshmen, who took Algebra in the Fall.
I do lots of “reasoning” preparation before we get to points, lines, planes, postulates, and proof…
So here we are, in March, delayed start (delayed by choice), following our text (Jurgenson Brown Jurgenson) pretty closely, and the text goofs, big, and the kids have enough preparation that they do what the book implies cannot be done. Well, two of them do. But they’re 9th graders, right?
What the hell is the Parallel Postulate?
When I was in school, I thought it was “given a line and a point not on that line, there is exactly one line parallel to the given line passing through the given point.” According to our textbook, the postulate they offer is “given two parallel lines cut by a transversal, corresponding angles are congruent.” And then there’s Euclid. Strange