Biology, advanced biology, and German.
Freshman math/algebra was a disaster. I didn't do very well, and I thought I just didn't "get it." The teacher was in her first year. After her second year, she got fired. It turned out there were a whole lot of us who hadn't gotten it.
Geometry in sophomore year was OK - I liked it, thought doing proofs was fun, and did much better. Trigonometry was pretty good in my junior year. Last marking period of senior year math was miserable. It was an intro to calculus. The teacher handed out a slender black book about the size of a 5x7 card and said, "Here - this is all self-explanatory." Au contraire!. Only thing I ever got an F in. Self explanatory, my ass. At least not to me.
I didn't warn my parents about the failing grade. My mother was aghast, and certain that the colleges that had accepted me were going to rescind their offers of admission.
I was also in the band all 4 years, playing flute and piccolo. We got graded in band, but there was no academic credit attached, so an A in band did nothing to balance off a C in any other class, and did not do anything to either help or hurt your GPA.