Do you have a favorite? A lot of my students say they remember liking "the old a-squared b-squared". . (who can guess what that's referring to??)
Personally? I have always been a sucker for factoring polynomials. Loved it when I was in school. Went NUTS when I saw "new methods" to solve them when I became a teacher. And secondly? I remember really liking the processes that feel like magic. Things like synthetic division, or the binomial theorem. . . processes that almost demand "TADAAA" at the end of it. My brain has scripts that play as I synthetically divide. . ."put it in the box. . . coefficients.. . . . drop. times, subtract, times, subtract, times, subtract. . . TADAAA!"
What are your favorites? Or, for the kids for whom that isn't a reasonable question, tell us 2 things you remember about math in general, if there aren't any that you remember liking.
((Follow up -- let me know if you want to know more about the mathy sound bytes that go on inside my noggin.))