I was at a table full of kindergartners playing with triangles, trapezoids, and concave hexagons. We were building and chatting. They wanted to know if I wanted to hear them sing in French. I said yes. The sweetest two minutes ensued as this table’s Frere Jacques spread to the next and then the next, and soon the whole classroom was singing and doing math.
A few minutes later I made this.
And then I went scrambling for my notebook.
Yup. Sure enough. is equivalent to the Pythagorean Theorem.