This animation, along with encouragement from Hung-Hsi Wu, got me started doing youtube videos to help kids (maybe their teachers too) get a better feel for math, geometry in particular. A lot of kids who struggle in math don’t picture what’s going on. Doing geometry with no picture is like trying to work on a computer with no monitor connected: you’re in the dark and you stay there. This short animation is one of my attempts to help kids “get the picture”.
Links to this video appeared in Wu’s “Teaching Geometry According to the Common Core Standards” and “Teaching Geometry in Grade 8 and High School According to the Common Core Standards”, both of which you can download (for free) from Wu’s homepage, https://math.berkeley.edu/~wu/.