Gilrs, i need your opinion on this one. please answer?

im a junior in high school. there is this girl who i like a lot. i went to homecoming with her about two months ago. but now she confuses me. i ahve first hour study hall with her and i will walk in and she will look at me and then look away. sometimes in cl she will look back and smile at me. but most of the time she will make the eye contact and not even say a word. i will have to start talking to her. she never really starts talking to me. when i talk to her she will smile and be friendly but today she was talking in study hall telling her friend how she asked this guy to sadie hawkins. she was talking loud enough so i could i hear. but she will look at me in gym and in the halls. i dont know what she is doing. any ideas??