So, I had this one teacher in 1st grade and, I swear, some of what she did must have been illegal. Once, I was late to school BY 5 MINUTES, so she made me stay in for lunch. And no, it wasn't just for a bit, she didn't let me get food at all.
Anyone who got one single question wrong on an assignment would get called to the front of the class, get their paper torn up, then get yelled at in front of the whole class - more yelling if you cried at all
If you talked at all, dropped a pencil, or anything, she would send a note to your parents, completely exaggerated what happened, then humiliate you in front of the class - she did that a lot
When I was in forth grade, she brought a student outside, and said "Throw the crayons. Show them what you did in class. Go on, throw them." Turns out, she dropped it in class, then had to throw crayons in front of the entirety of 4th grade