How to approach a guy you know of but don’t know well?

This is a problem I’ve (15F) never been able to figure out. There’s a guy (15M) who I share a few classes with that I’m interested in getting to know. We’ve had a few very brief interactions. No formal introductions, or interactions that lasted longer than a sentence (two being generous). We’re past the point where it would be necessary to do formal introductions, but not at the point to go up and start a conversation about anything interesting.

He’s not a social butterfly so it’s not a matter of not having a chance to approach, but how. What would be a good way to go about it? Right now I’m thinking of just going up and asking an interesting question that could spark an interesting conversation. But my track record with guys is very bad and I do not trust my instincts at all.