so, i spend a good amount of time talking to a girl@school, and was wondering, if she is looking at me during class should i make eye contact?

i know this is true for women you haven't met yet, but what if you already know them?

yup. shows confidence and dominance. and smile.

if you have her number then you can text her and say "stop staring at me!" then look at her as she gets the message and wink at her or something.
i use it often in bars where i sit opposite girls i've already met/n-closed, havent tried it in class though so let me know if you try it.

id agree with the above poster, i tend to prefer not to do much more in classes than smile and add the odd comment/txt if appropriate since im mainly there to learn

Shoot, you guys have your priorities straight in class. I'm always talking up a storm. If the girl is staring at me from across the room, I'll mimic her body language. Let's say she is sitting at her desk, with an elbow on the table supporting her chin. I'll catch her staring and put myself in the same position. I always get a good response when they realize you caught them staring at you and you can start a conversation via txt or whatever.

BTW I assume you are in high school because of the way you worded your post. I can only comment on that since I dunno about the environment of college.