Why would someone who is unavailable send someone else signals?

Alright, so I have this class with a girl, actually two classes. I usually sit a row or two behind her, and during the semester I have noticed on various times her moving her head to look back at me, probably an average of five or so times per class period. Sometimes when someone else walked into the classroom, she would look in that direction, then use that momentum I guess to turn her head and look in my direction. There have been a few instances where she would look at me in the eyes, then when I looked back she would quickly turn her head, whatever. There were times when I was walking in front of her I sensed her staring at me as well. I never really engaged in conversation with her, but before class I did engage with her friend, who she was standing next to, and the couple of things I said made her chuckle rather astutely (her friend too).

Ok, so I am in another class with her, but this one has like 500 students in it so I never really noticed anyone in it. The other day, when practically no one showed up due to the holiday, I saw her with another guy who I was able to confirm was her boyfriend. Though in the classroom, which is a pretty large room, like an auditorium, I believed I saw her looking at me from across the room.

What do you think is going on here? Maybe I am really terrible at reading signals? Although I feel as if these occurances are too frequent to be mere coincidence.

sometimes girls just like tease guys, just to check if they are still in shape of getting attention, and if you dont give her attention she'll try even harder
is she a good looking girl?

She probably thinks you are attractive. Girls notice attractive males too, you know. Just because she looks at you doesn't mean anything (unless she is suggestively sliding her tongue across her lips, or something).

Girls are whores, thats why. Never is enough.

She doesn't seem like the type that would flirt just to enhance her ego. She seems like she is sweet, sits at the front and minds her business in class. The signs that she shows seem to indicate that she has some sort of attraction or crush on me. And that's the problem. I am beginning to think that I am just really terrible at reading signals.

From what I have gathered, she has had this boyfriend since high school (she is currently a freshman in college). Do you think the change in scenery could have something to do with it? Blah I don't know. The whole fact that she has a boyfriend already just seems so inconsistent with the whole situation.

Stop worrying about what she is thinking. Just tell her that you wish she was single so you could ask her out. She's not married, and until she is, she still has a choice. If she loves her boyfriend, she will choose him.

There are lots of possibilities, Channels:

1) She may simply be indulging her attraction to you in a harmless way;
2) She may be unhappy in her relationship and is trying to get you to express interest so you can help her out of it; or
3) You may be simply misreading her.

Regardless of which is true, your response should be the same ... indifference. Pursuing someone who's in a relationship is always a bad idea.

Now if she breaks up on her own, and after a reasonable amount of time has passed (a few months to avoid being her rebound or fallback guy) and she's still unattached, go talk with her!

Carl.