How should I talk to him?

There's this guy in my medical terminology class who seems to be attracted to me. It's a super small class- only 6 of us. Well, he's usually a really goofy guy who is really nice. He acts really shy around me though. Every time I enter the class I always catch him looking at me. I used to think he had a problem with me (me being paranoid and all) but that's just not like him. Also the way he looks at me just seems different. I am never attracted to guys like him- I usually like the quiet and rebellious guys... He just seems different though in a way. He sends some mixed signals and I really don't know what he's doing. How do I start talking to him? He added me on Facebook like a week after I got in this class (I changed classes). I'm a junior and he's a sophomore...