Abandoned (2001) aka Torzok

Aron is a happy child in his family. But at some point things take a different turn, and his mother starts to lose her health rapidly. As this happens, the man in charge decides what's best for Aron without consulting the young boy's opinion, and the boy finds himself thrown out of his warm home into an orphanage in the woods. He's utterly displeased by what's happening, without knowing he has yet to face much worse. After a hard time getting over the harrassment of his classmates and being accepted as one of them, another obstacle on the way to his peace of mind faces him: His obnoxious teachers. He has no intention of being bad, but it's beyond his ability to blend into the revolting place he's in. The nasty treatment of the teaching crew gets the better of him, and he's not all that calm and passive anymore. But that leads into unpleasant events which Aron himself wouldn't want.