sites.math.washington.edu/~mathcircle/
sites.math.washington.edu/~mathcircle/
https://davidson.weizmann.ac.il/online/mathcircle/clips/%D7%90%D7%99%D7%9A-%D7%9C%D7%91%D7%97%D7%95%D7%A8-%D7%AA%D7%90-%D7%A9%D7%99%D7%A8%D7%95%D7%AA%D7%99%D7%9D-%D7%91%D7%93%D7%A8%D7%9A-%D7%9E%D7%AA%D7%9E%D7%98%D7%99%D7%AA
https://davidson.weizmann.ac.il/online/mathcircle/clips/%D7%90%D7%99%D7%9A-%D7%9C%D7%91%D7%97%D7%95%D7%A8-%D7%AA%D7%90-%D7%A9%D7%99%D7%A8%D7%95%D7%AA%D7%99%D7%9D-%D7%91%D7%93%D7%A8%D7%9A-%D7%9E%D7%AA%D7%9E%D7%98%D7%99%D7%AA
I like the ideas of classifying what's going on, figuring out which cases are "the same" in some way, trying to figure out why starting with a triangle is different from a square in terms of what can happen.
I like the ideas of classifying what's going on, figuring out which cases are "the same" in some way, trying to figure out why starting with a triangle is different from a square in terms of what can happen.