I think every teacher reaches a pivotal point in his or her "career," if that's what you call what I'm doing here, when he or she stops trying to change the assholes and instead merely copes with them. As any unhappy wife or husband can tell you, it's damn near impossible to change your significant other in any significant way unless he or she decides to do so himself or herself. Sure, when you teach you can make some sort of impact on a stupid student who is interested in learning, ready to pay attention, and responsive to guidance and criticism, but good luck trying to change that stupid kid who thinks he's (almost always boys) smarter than you and gains nothing substantive from school whatsoever except a few Zzzzs.
So, as a teacher, you learn to pick your battles. Let that girl or boy sleep. They're always talking to their friends when they're not. Let that girl hit the boy on his back as hard as she can. The boy probably deserved it. Let the two boys in the corner make some inane joke about the teacher, because frankly if you care what any 16 year old has to say about you, you have no business in the teaching profession.
I have a girl in my class at the local high school, who is quite bright, but insists on drawing Japanese anime with every free second she has. She's quite good, but I'm concerned that her social skills might be suffering as a result of her hobby. We can't all be butterflies though, so I usually let her be. She's quiet enough and doesn't talk to her peers too much and when I ask her to participate, she does so willingly and usually provides the right answer.
The other day she was hunched over in the corner, working diligently on her new comic masterpiece, as I was trying to rein in the herd known as my class. Teaching a class like this is more cattle driving than lecturing. You organize them all into the center and establish some semblance of order, but inevitably a stray cattle wanders off into the distance and the process repeats itself.
At the end of class, all of the students filed out of the room until it remained only me and anime girl. She shyly walked up to my desk, and said quite meekly, "Here, teacher. This is for you."
I open it up, and lo and behold, her anime masterpiece was actually a very familiar sight: