Back in high school I had one hell of a math teacher. He instills fear in students and uses it as a tool (ala Batman.) His class scars me to this day. Examples of the things he did:

1. Asked students to answer while "feeding" them bits of information that lead to the answer. Sometimes he could be feeding you the wrong one, or he could be telling you the right one. We used to be able to tell from the tone of his voice but soon enough he caught on and the strategy was useless.
2. In the first semester (we have 2), he was not afraid to go back and edit our grades if we couldn't answer his questions. If we messed up multiple times we could kiss our grades goodbye. He later stopped this.
3. So much homework. I don't want to sound entitled or anything but it was a ridiculous amount of homework. We used to have a Discord server with a voice chat that usually ran from 8PM-2AM most nights. Some nights it ran even later. Most of the time if we were studying, we would be discussing math problems.
4. He was not afraid to let loose if you messed up. He was the Gordon Ramsay of math teachers. His class featured insults like "Hey I heard you went out yesterday. What? You forgot your brain there?" Or "Don't say sorry to me say sorry to your report card."

That barely scratched the surface. I honestly can't fully convey the suffering we went through in his class. You have to live it to fully comprehend it. It was suffocating. We did make a couple complaints but that only unleashed the beast even more. It got so bad some parents had to step in. I know my and my bff's did. They asked him to lay off us. He got an earful from my friend's dad. He treated us a little better after that but still, his class induces a fight or flight response like no other. Thank god we only had him for a year.