So - first of all: do a forum search. There have been many, many threads just like this one where some really smart guys have already answered this question.
Secondly - the short answer is: Man up, and man up now. Don't wait. Doesn't matter what you say to her to open (seriously - a great opener is literally "hi").
Do I think you're going to do this? No (I would love it if you proved me wrong too - I'm rooting for you

). You'll argue logistics and wait 2 months until school is done. You'll argue you can't do it in the hallway, in class, outside, etc... (See - we have had this topic a few times before

)
So now search for "isolate" in the forum search... Then man up.
Good luck!