I'd have to unconditionally say it was Mr. Webster, 9th grade Algebra 1.
It was more like the class from hell on stick and same goes for the lizard he rode in on too, and his quizes and exams are what true nightmares are made of. It was an interesting and engaging class however it was frigging evil starting with 3 hours of homework on day one of class due the next day. We even had homework due on the last day of class then was given another several hours of homework to do on our own after school let out without it ever being graded. Like I said, frigging evil.
He taught at a college level in high school so you would be ready for college. The year long Algebra 1 syllabus was complete before thanksgiving. We then went through the Algebra 2 syllabus by christmas break, then we were assigned lots of homework due the day we got back to class after the holidays. Then we had a whole spring to do whatever he threw at us next. Turns out it was trig, geometry, imaginary numbers with a vengence, mathematical concepts of physics equations and the 100 word problems from hell just to prove that we could do the impossible that everyone else freaked out over. At some point he was showing us something and said most of us would never ever see it again but those who do see it will know how to solve it and we will thank him for it. (I can still remember his face after saying that to this day) He made each and every one of us do the related problems and understand thoroughly what we were doing and why and how it worked..then he went onto the next subject. He never would tell us exactly what it was other than it was an exercise in numbers to give us self confidence and understanding. I was one of those few that found out what it was. About halfway through Calculus 3 in college everyone's brains in the room went KABOOM, brains all over the wall, no survivors, they're all dead jim, jim, hey jim, jiimmm, um, jim's dead too. My instructor turned around to look at the expected bodycount and got it...MINUS 1. He had the most confused look ever...I was just sitting there calmly smiling because I knew how to do that stuff like it was basic one digit addition. I had already had it rammed down my throat for almost two weeks in 9th grade.
Sadly, Mr. Webster got fired the year after I took his class for not giving out the administration's required quota of A,B,C,D,F's in his classes. Our grades in his class was what we earned and deserved and we all knew it. All the HS math after that and some college math up to a point was a complete total blow off. I was one of the many ex students of his that when we heard he got fired and why, that descended on the school board for committing high treason.