Never had to. I was always the 'smart kid' in class and received high marks on tests either by memory or just by using simple logic. Granted, I usually got ****** grades because I ditched class all the time and never completed any homework assignments, but that's completely irrelevant.
I tell ya though, I came to the conclusion that I live in a town full of really stupid people after I went out into the real world and wasn't always the most intelligent person in a room. That, or it was all the pot I smoked as a kid.