I like this girl but I don't know if she likes me?

I'm not really sure. A lot of girl's laugh at funny things guys do. But that's always a good sign! Try flirting with her more, tell her she's cute, and see how she reacts. Or you should just straight up tell her you like her. That's always a cute thing to do. But only do that if you think she might be interested in you! To start it out, just ask her to sit with you at lunch and see where that takes ya. :)