To add on to what Jespah says - you have something in common and a conversation starter already - the same class(es) you are in.
Ask her a question about the class....did you understand what the teacher said about xyz? I really liked today's lecture ===
Hey do you have the next period off -do you want to hang with me and get a coffee? We could review the next assignment together....
This could work with anyone not just someone your attracted to in a way to make friends