Today I decided that I wasn't stimulating Arthur enough. "Arthur, do you want to play with right triangles?" I asked.
So I got some red and some purple construction paper, scissors, and a paper cutter. I cut strips of red and purple and began to cut them into right triangles.
"Arthur, no; don't rip the strips. I need them to make triangles. Is this one red or -- No, don't scrunch the triangles. Scissors aren't for Arthur. Wait, buddy, that paper cutter is sharp. DON'T eat the triangles. See, you can make a pinwheel out of -- hey! Keep those on the table. I said the paper cutter is sharp. OK. Look, see how three triangles makes a -- eeuw! Don't blow spit on them, that's gross. OK. Nice try with the scissors. Look, I'll arrange these triangles, and these triangles are for you. I think I can make an octagon; don't blow mine off the table. Blow yours off the table." (Why God, Why?)
Of course, I thought maybe I'd have better luck with wooden right triangles; except that they'd have to be wider than four inches at their narrowest point. And speaking of points, everything would have to be bevelled to prevent its ready insertion into an eye.