Were you in my math class? Now seriously, I came here to write the exact same story, except I only had this teacher for only year (thankfully). My next teacher wouldn't believe us until he saw our first test results but he wouldn't speak ill of his coworker. He was so amazing we ended up learning everything in that single year, and I went from about to fail to an almost perfect score.
Haha! I don't know, but I hope so, it would mean there was only one such terrible teacher known. ;-) Mine's name was Fernande. It happened in French Canada.