Last year at college, I went into lessons high as a kite nearly every day, I was surprised to find I had actually achived good grades (my teachers wanted to kick me out of the course I'm doing). It does make the lessons more interesting, and I found that I actually worked harder (I was paranoid that I'd get busted for bieng wasted, so I worked my ass off). This year, I'm gonna go to all my lessons sober and see if I can do even better.