This is an assault. Teacher could have fallen, or fallen on his head and received brain damage. If he had fallen on the floor, the student probably would have kicked him in the head. This is the way these Amish fight.
This should be a law enforcement issue.
And, why is the teachet’s face shown, but the perps blocked out?
IMHO the teacher did a good job of falling to his knees and yelling as if in great pain. Probably theatrics for the cell videos.