The coin around coin problem has its own wikipedia page, although some people want to delete it:
I hope they don't. The argument for removing it is basically that if you understand geometry, then the conclusion is obvious; but since this is an area where most people's understanding of geometry is incorrect (myself included, before today), the article is valuable. I don't see how it's different from articles on other mathematical paradoxes (Simpson's paradox, for example).
[0]: https://youtu.be/oEN0o9ZGmOM?t=523s
[1]: https://www.scientificamerican.com/article/the-sat-problem-t...
EDIT: I don't want to stop animations permanently with about:config; I just want to pause and un-pause.
https://addons.mozilla.org/en-US/firefox/addon/toggleanigif/