What does his staring mean?

First of all, how can you tell if a guy is starring at you when he's wearing sunglasses? This guy rarely looks at me unless he's wearing sunglasses. I've caught him a couple of times during class(when he's not wearing sunglasses) where he'll just blatantly stare at me, but it will be with an emotionless face and it'll feel like he's studying me or trying to look into my eyes (hope that makes sense) I'm the one who ends up breaking the eye contact ...Then other times when we'll be waiting for class to start he'll sometimes have his sunglasses on and I'll look over and his body and head will be in my direction and it feels like he's starring but then again, hence the whole sunglasses question, I can't tell if he's really looking at me or if I'm just wishing he was. When I saw him for the first time, every time I would look at him, he had the same position with his head and body in my direction, but I wasn't sure if I'm just catching him starring off into space, or if he's interested in me at all. And I'd also like to add that he doesn't seem to be shy around people.