Does this girl like me?

In my first period cl I see her and she looks at me and smiles so I smile back and she looks in to her book I also talk to her and she laughs at all my jokes and I am starting to have a crush on her and I just want to know if these are sighs that she likes me and she also like fliers with my friends when I'm around but never when Im not so should I ask her out or no?