First things first, violence is not the best course of action, you should try to talk your way out of any physical confrontation if possible. If you are attacked, the point of the chin should be your primary target, it doesn't even have to be a hard punch, just a clean short hook to the point of the chin will do the job, but I have to tell you that it is best to avoid violence if you can.
back of the jaw where it meets the ear instead of striking with the hand a clinch and knee are far more effective use elbows if he is bigger and likes to rush good luck
you are silly and will get in trouble. you cant really "teach" anyone how to break a jaw. plus, even if you did, your parents will be held liable for his medical bills, and you might get expelled.
A kid in my school started a fight last week against me and swore to fight me tomorrow. He had been expelled from school because of the fight for the week and I really need to somehow break his jaw. The teachers at school won't care because he started the fight. So, the big question is how to break his jaw and where abouts on his jaw? Please include a photo of the location of where I need to punch him etc. please don't say I'm silly and will get in trouble, if you want 10 points tell me how!!!!