I woke up this morning so excited to do math, because I had this awesome idea: build triangles to practice subtraction. Monkey's been exploring two-digit addition and subtraction, and we do usually do these problems with rods. He calls them "tricky math." Today, I threw in a twist by showing him about degrees and building a triangle as he subtracted from 180, which I had previously given him. He could choose any numbers that made him happy as he was subtracting, and I drew the triangle that went with them.
I did the writing because (A)I was drawing the triangles, and (B)that kind of "tricky math" still requires a lot of concentration for him to do, just counting the rods. But, he liked it well enough to do again; he wants to do rectangles tomorrow. That's going to challenge our set of rods! And, not so incidentally, he got some exposure to geometry concepts this morning, in a fun way.
I looked up the sum of the angles here, and I'm sure that I'll be back to that page as we play with more shapes; they have quite a few. I think that building pentagons would be fun, but we'll have to work our way up to that.