From my own experiences - you are never going to know if she likes you if you don't speak to her.
In the situations you have described, there is nothing in them that seems to indicate feelings towards you one way or another - positive or negative.
If you are in the same classes as this girl, there are plenty of things you could talk to her about. Realistically, for her to like you, she is probably going to need to get to know you. Ask her a question about an assignment. Say hello to her when you see her. See where it goes from there.