A lot can be determined from body language.
Body language signs of a boy liking a girl include watching her when he thinks she's not looking, smiling when she catches his eye, leaning into her space when they talk or touching her in gestures that appear casual. A shy boy might get fidgety around a girl he likes, blush when she looks at him and struggle to speak when she talks to him.
Many young boys find it difficult to communicate with girls they like, so they might turn to safer options where face-to-face talking is avoided.
If a boy texts a girl a lot, or pursues her on social networking sites such as Facebook or Bebo, it can be a sign he is romantically interested in her.
Usually the first people to know if a boy likes a girl are the boy's friends.
If the friends start to tease the boy when the girl is nearby, such as making jokes or playfully encouraging the boy to approach the girl, it can be a sign he likes her and has admitted as such to his friends. Social teasing also applies to the crush--a boy who frequently teases a girl is often trying to get her attention.
Arranging Time Together
If a boy likes a girl, he will often go out of his way to be wherever she is.
He will frequent her favorite places, such as when she's out shopping with friends or attending get-togethers, and he might make a point of being near her at school and when they go to lunch. A boy with a crush who is too shy to ask the girl out might arrange a social event, like going to the movies or a party, and ensure the girl and her group of friends are attending.