Oh, where to start?
I went to 1st grade in another country. The teacher spoke another language I could barely speak, and could not write at all. When she started in on the written lessons I could do literally nothing. She came over and I told her I could not write in that language. She didn't speak English and made a big scene in the class with the other kids literally standing behind her pointing at me. I was getting no help, and feeling obviously pretty alone, so I started to cry. She went on and on and her tone was not consoling, let me tell you. When my Dad picked me up later I noted she spoke perfect English with him.
My 5th grade teacher would pick on one other kid and me for not having homework done. The other kid was a dumbass; I was smart but for obvious reasons to follow was not able to contribute much. He would call each of us up to the front of the class and berate us. He would usually let the other kid off, but with me he would berate me until I started choking up. Then he'd push me up against the blackboard (physically shoving me in the chest) over and over until I was crying. This went on a long time, not sure how long. I hated that guy, but I hated those other kids even more. Not one of them ever told another teacher, the principal, or a parent.
Once in about 6th grade, a kid jumped from the top of the monkey bars and smashed my head into the frozen playground. I awoke on the ground with a spitting headache, cursing. The kid had taken off, but a girl saw the whole thing. She told my teacher I had been swearing and I got detention. When I tried to tell him the story, he cut me off and said there was simply no justification for that kind of language.
In HS, I was late for class because I had been with the counselor (obviously, given the above issues). I had a written excuse. The class was taking a test and I took it and finished just a few minutes after everyone else. When I turned it in, the teacher would not accept it because he had called for the tests already and I had failed to turn it in. I reminded him I had given him an excuse for being late, but he didn't care. I never understood what the "excused" tardy was for if not for that.
Also in HS, I never received my JV sports letter. At the start of senior year, I went to the athletic director, who had been assistant athletic director the year before. He wouldn't give it to me, and said he had no proof I had participated on the team.
TL;DR - various fucked up memories that destroyed my faith in the educational system and various humans in general.