Have you read The Game? If you have, flip back to the section where he interviewed Brittney Spears. This is going to be your guideline for how this should play out.
Begin the conversation with solid game. Talk to her, get her attracted, and use "we should probably start studying" as your time constraint. Then, when you take study breaks, every 20 minutes or so, go back into game mode. Use negs, lines, routines and whatever else you need to build attraction, but instead of saying "well, I need to go meet up with my friends now," you say "time to study," or "let me show you this one thing real quick, and then we'll get back to studying." When studying is all said and done, see if you can transition into a date "hey, since we're already out...." or, when after the test, say "Since you did so well, I'll let you buy me a drink to celebrate."
Man, after reading what I just wrote, I REALLY wish I'd know about this stuff when I was in college. Good luck!