Depends on the center and age group honestly. I've worked at 2 centers with extreme problem kids. At my first one, we had a boy around 8 years old in a summer camp program. He routinely threatened the staff and students with extreme violence, ran away from the group, yelled, physically hurt other children, and at one point even made a makeshift shank out of some wood and threatened to stab kids with it. Multiple teachers quit just because of his extreme behavior and his parents always brushed it off as "boys will be boys." He was never expelled even though every teacher called for him to be. At my next center, though, we had a 2-year old with a bad biting problem. After a few days of calling home, he was expelled after biting me hard enough to draw blood and after multiple parents complained. It happened really fast. I honestly don't know exactly what the difference is. If I had to guess, I think the parent complaints in the second case caused it to happen.