Andrew Clark (Emilio Estevez)’s Timeline and Summary

Andrew's dad drops him off at the school for detention—chiding him for putting his scholarship at risk.
Soon, Bender and Andrew end up verbally sparring, with Andrew defending Claire and insulting Bender, calling him a nothing.
At one point, the argument gets so intense that Bender pulls a knife on Andrew, but doesn't use it.
Eventually, Andrew ends up smoking pot with Bender and the other kids.
When they sit around in a circle, Andrew reveals why he was really sentenced to detention: He horribly bullied a kid by taping his butt cheeks together, inadvertently causing skin and hair to come off when the tape was removed.
At the end of the movie, he ends up getting together with Allison (after her makeover), acting on the chemistry they've felt for each other throughout the course of the movie.