How do you get a 13year old girl that's like when shes around her friends she acts like she don't like you but when shes not around her friends she does?

When she is not with her friends say- I like you a lot. Wanna go to the movies? (or just the second part) if ur parents don't know, ask her out. It's easier by phone or txt. If she says no talk to her. You got nothing to lose. Ask her why, and say you noticed the thing about her friends. Say that she doesn't have to tell them if your going out with her. If she still insists not, say- I won't tell anyone, not even my friends, but I just wanna know, do you like me? And you just don't want your friends to know? If she says no, she is probably lying