Which movie is this? Read Description?

This movie is inspired from some actual events. Group of school students, lock down school staffs and parents in the school. And then they trash down all the cars outside. Next day, most of them get arrested except a boy and a girl. They wave at these fellows who got arrested.

So if you found it let me know, it's one of my favorite movies.

Yes I have watched the entire movie, but now I forgot the name of the movie, also the entire story.

Also I think there is a scene, where a teacher who is locked inside see's a boy who is mute, asks him for a telephone, he then brings it and give it to her, and he skates away [I think he was skating] .