Physical Danger
If you're telling a football player who is three times your size that he can't play the big game because he got caught cheating on a test or is failing Algebra, you might want to make sure someone walks you to your car that day.
Violence in schools is always a possible threat, however stats show school is actually the safest place you can possibly be—unless there's a measles outbreak and you haven't been vaccinated, of course (source).