That is also terrible teaching. A good teacher sets up a productive classroom environment from the beginning, with expectations set out in words and also modele

That is also terrible teaching. A good teacher sets up a productive classroom environment from the beginning, with expectations set out in words and also modeled in behavior (calling on a wide variety of students, modeling how to ask questions about a student's thoughts, modeling how to give praise and criticism, giving a continual example of how to work through problems). When issues like negative interaction between students come up it's easy enough to set up a group work lesson that separates problem personalities, put people in groups with supportive folks, leave alone students who want to be left alone and try to channel energy in the right direction. I've worked with nerdy teenage boys and socially awkward types of all genders, and it's a matter of skill to deal with this but that is after all the job! For instance, I had a student (13 yrs old?) in an advanced math class that was all male (I'm female) and he had a habit of starting to blurt out mildly veiled sexual comments to me. I said a few things to him about what was appropriate in class, in a kind way and privately, and I also arranged for a male administrator to chat with him. It stopped. Grades have nothing to do with this -- they're not effective in any way in setting classroom tone, especially as they're feedback far after the semester ends. I'm sorry for all these Hacker News readers who had shitty high school experiences, but you do need to grow up and realize they were shitty. Turning around to dump the shit downhill -- or indulging in some sort of Stockholm syndrome -- is not going to make the world a better place and it does not make you a better person. I don't always do things perfectly; I remember one female student who was being aggressively and unwillingly courted by a football player in one of my classes and I wasn't able to prevent all the distraction. But I noticed and did what I could, and commented to them separately about what is and isn't alright in the classroom. Seriously, folks, it's not that hard to have expectations for appropriate behavior and enforce them.