What can a stare mean? I like her and im not sure if a stare means the same help please?

Alright. so today was the first day of school. i get into my homeroom and a girl that i had talked to a little last year was staring at me in homeroom, in gym, in french, in social studies just staring. and at lunch i stared at her a little and she had all her friends staring at me. she smiled and turned around and i just shrugged it off and returned to my friends. What does the staring mean? I mean... she's not all that popular so she may be shy but she is really pretty and nice.