There is this girl in one of my classes I want to talk to but I don't know how I should approach her. In class we don't do anything but hangout because it's an ap class and we already took the ap test. Any ideas how I could approah her that wouldn't make me look like a total creep

I don't know if you have assigned seating, but if you don't, sit near her. At a time when you aren't doing anything, strike up a conversation with the people around you. That way it wont seems like you're pouncing no her. While you've got a conversation going on between you and the other kids around you, pull her in. Ask her how she did on her test or what her plans are for the summer. Just be cool and casual about it. :)