I did the same. The school systems were undergoing a transformation to dumb everyone down, and it worked on most. If I hated a teacher, I would do nothing in class, only do projects if they counted for a good chunk of the grade, and just do well on exams. If I liked the teacher, I would speak in class, get the teachers talking and going off on tangents so often that they would run out of time and not be able to assign us homework because they didn't get to finish the lesson. If I REALLY liked the teacher (and this was only 5 of them in total that accepted this deal) I would tell them that I didn't want to do the work, and they probably didn't want to grade the work either, so made them a deal: Give me my grade based 100% on the final exam and I'll accept it whatever it was. That worked out nice for me.
My family moved around a lot (from K-12 I was in 8 different schools, the longest was 4 years in any one place) I got to see a bunch of different ways of doing thins. Nothing was more infuriating than going to a new school, a grade higher and then being given work that I did 1-3 years before then. Having to waste my time because that area was raising retards and more advanced in the liberal dumbing down of kids. Sometimes I wish I could have been homeschooled, but at least I have some close friends that have been in my life for almost 40 years now.
My wife has some similar stories about moving to a new place where the schools were just complete trash. Like, sleep through the classes and get an A and where she came from you would be lucky to get a B- busting your ass every single day no matter how hard you tried.
Those were typically the science teachers who were retiring at the end of that school year, and had no more fucks to give. I had a guy in my class who was by far the biggest nerd in school, he got 100% in every class that he ever took EXCEPT that science teacher. He only got something like 82%. They all have the same kind of look (kind of like Colonel Sanders) and I was able to quickly identify them and drop their class after a couple of days.