How to tell for sure if someone's staring at you?

So I like this one guy and almost every day and see his head turned toward me like he's staring at me but I get to shy (I just do okay) to turn and see. So how do I know if he's staring at me or looking somewhere else?

Smile at him. Make funny faces.

Yawn. A lot of the time yawns are "contageous" and when someone sees you yawn they will (most likely) yawn back. So fake one and see what he does!

If you have an iphone just hold it casually in your hand. Make sure the camera is turned on and the screen brightness is all the way down and causlly hold it in your lap so that its angled at him. Look like youre paying close attention to the teacher and press the volume button (iphone 5 takes pic this way)(make sure volume is OFF). Look at the pic later. (delete after <<<<lol important!)
You can also ask for a friend to look for you.
Or wear sunglasses and you can look at him and he'll never know lol.
Turn and start a conversation with someone who is next to him and you'll be able to see.