you can tell that a 10 year old girl likes a 11 year old boy by the way she may try to avoid contact with him, but is always staring at him. if that 11 year old boy is already going out with someone, then the 10 year old girl may try to get info about the relationship by asking the 11 year old boys' girlfriend.
How do you get an 11 year old boy to like you if he has a girlfriend but you call him a lot ps i am 11 too but he is breakin up with his girlfriend?
No offence, but I wouldn't really bother. He's 11. Even if you do manage to get him to like you, it won't be more than holing hands and breaking up after a month. Even so, you can't make him like you. Especially if he has a girlfriend. It's immoral to try and make him like you if he already has a girlfriend.