My old math teacher once tied a pencil around a student's wrist so tight that it cut off circulation, just so they wouldn't lose their pencil. And this was in 5th grade, so we were young kids...
From current teachers, my spanish teacher cuts half credit from an assignment if it is even a minute late, and yells at students for no reason. On top of that, she fails more students than any other teacher in the school.
13 more!