If he feels like you are waiting for him to talk, he probably gets all nervous. When you get to class, make eye contact, give him your prettiest smile, say hello and then just sit down. Occasionally drop a compliment (I like your shirt). Don’t keep glancing at him. If he feels like all you do is look for ways to get his attention he will get scared. Guys like confidence. Let him see that you have things to do besides think about him. Guys like a woman that plays hard to get!
Good luck!