I had one prof who made the class a good deal harder than the others who taught the same class. Students fled in droves but a few of us stuck around and learned something (and no, I didn’t earn an A). Profs like that who raise the bar should be encouraged, other profs who use their position to exercise their prejudices, like the various anti-American biases I’ve run into in an American college, should hit the bricks with no delay.
My best professor was hard as hell, but he turned me into a problem solver. He used to call all his students girls. At that time we only had one female studying engineering. One of the proudest days in my life was when he gave us back an exam, and as he gave me my exam he said in a loud voice ‘You can leave Sir, I don’t want to waste your time while I go over this exam with the girls’. Most students hated him, but he was a great teacher. He would not last long in today’s pc world.