So, I don't love tricks? You know, the "don't worry about the why, kid, just remember this little song" variety. But we're in the weeds of finding areas and perimeters of composite shapes. Of the quarter-circle stuck on a rectangle stuck to a triangle variety. Yes I want them to have a intuitive grasp that the distance around a circle is a little more than three diameters, and yes I want them to see a circle deforming into a rectangle whose width is r and length is half a circumference. And yes we are mostly solving problems with tracks and whatnot.
Buuuut....I am not confident about how much of that they are going to be able to retrieve when they are sitting for their SAT's a year and a half from now. So, we are shamelessly using a trick, that a student heard somewhere else, for keeping circumference and area of a circle straight. "Chocolate pi is delicious, and Apple pis are, too." I'm storing it in the same dark place as "All Students Take Calculus," as in, it makes me feel a little dirty, but it seems to be a necessary evil.