Does she like me? If so how do I proceed?

There is this girl in my chemistry cl. We're both Sopres in High School. I really like her, and up until now I thought she liked me. We talk a lot and always play games together when our teacher is droning on. When ever she sees me in the halls she smiles at me. She even told me she wanted to hang out some time. But.... She seems to be avoiding wanted to hand out. First she had a party and said she couldn't make it. However when the party got cancelled she told me she had to help here dad make a movie. Now she is telling me who she likes, and that is not what I want to hear. What am I supposed to do? Does she like me?