My education system did teach me this proof ! When I was in Grade 6 or 7 (11/12 years old) we were told to cut up a paper circle into sections and line them up head to tail. We kept making them smaller until the shape became like a rectangular. I still remember it, it was one of only two “aha” moments I had in my entire math education. Fully agree with you that we need more of this, thanks for your article.