How can I tell if he likes me by body language?

It could be both. Does he do the same with other girls? If he treats you differently then he could definitely be into you. I have had good guy friends who did all of the above ,but never saw me as more than a friend. We just had a really good connection with each other. Does it seem like he can't get enough of you? What do your conversations entail? Do you hang out outside of school? You need to consider all of these things, but why don't you make a move if you really like him? he doesn't have to be the first one to make all the moves.

I think yeah he does like you because he is trying to get closer on a deeper level and maybe even touch your arm or something which most people who want a friend wouldn't act like that.