Is she a flirt, or is she serious?

There is a girl who i see alot at school. She recently sent me a friend request on facebook , and whenever i see her she looks away really quickly. The problem is, she hangs out with so many other guys, and unfortunately guys that are way better looking then me (im being modest). Is she putting herself out there for me, or is she a flirty girl who i should try and avoid? She always talks to other guys during the day, but focuses attention on me when im around. Im in ask a female because if you were doing this, would this be your intention? Thanks