Something I have indeed learnt from school

People who derive enjoyment from misusing their power to torment other people exist.

In my case, I was on the receiving end, and the abusers were teachers who punished me for trivialities such as being three seconds late in a circle of standing people. In 2016, I was threatened by authority-abusing sports teacher William Löbbert with being sent to the school director. The same teacher gave me a mark 4 (out of 1: best, 6: worst) in sports, whereas other teachers gave me 1's, which completely discredited the rating system. So yes, school teachers indeed successfully taught me a lesson for life by being the abusers.