How do you know if a girl likes you?

[Kevin]

Hi, im a 13 year old Guy. I like a girl in my class. Her locker is next to mine. I dont know i she likes me, but sometimes she says Hi in a friendly way and sometimes she is angry at Me for no reason. Yesterday Me and my best friend was eating at McDonald's. I took a table and my friend stayed in the queue (Line-up). When he sat down at the table he told Me that she and her friend was in the queue, i looked towards the queue and saw her excessively waving at Me and i waved at her. Later she and her friend took the table in front of us. I think she was looking at Me (she had her back against Us), she looked obliquely out of the window and sometimes looked behind her, at me.




On facebook, we have a group with everyone in our class, i have asked 2 questions about homework and she has always been the first to answers.




So, my question is: Do you think she likes me?



Sorry for bad english, im from Sweden.