Are you getting good vibes from her? Doesn't sound like it. I'd ask a friend out if I was getting good vibes from her and really got to know her. Asking her with the way things are is pointless, you're potentially throwing away your friendship on a long shot. I'd go for it if you were getting good vibes from her, though.
Are you just friends with her in school? If you don't ever see her outside of that, then I wouldn't even bother.
On the flipside, if you're not really that close to her and your friendship isn't that close, you don't really have much to lose by asking her out. But I'd keep things casual so that the two of you can get to know each other better without it getting too awkward.
Good luck, OP, I'm in a similar situation, only it's with a friend who I've known for years but only recently started hanging out with again. I think I'm getting really good vibes, share a lot in common in terms of interests and personal beliefs, and we flirt, at the same time I hear her say things that turn her off that I find reflected in myself (self-confident, conceited, vain). The stakes are higher when going for someone you're really close to and really really like, I guess, but I'm working on it step by step. Not going to confess my love or anything sudden or extreme, but slowly make things more intimate as we get to know each other. I find that works really well, your mileage may vary.
