The problem with this is not just that a kid is bullied; it is that the weakest in the pecking order is chosen by the others to be picked on. Usually there is a ring-leader. He is the bully. It is like onto a "gang" mentality. What one does the others must follow, in order to prove themselves or to "fit in."
This is animal kingdom behavior as well. The weakest in the flock or the herd is singled out to be shunned; then another species moves in and removes the animal that has been left apart; kills it and eats it. Tears it to pieces.
If you watch hidden camera videos of a group of boys (or girls...yes they do it too) as they laugh and playfully poke and push at each other, taunting one of their own to go over and "do something" to the kid that is different, is weaker, is of color, is gay, is of mixed blood, is deformed, has a disability, or whatever they have found to be "different" than they are, you would be sickened by the scene. Most often these scenes play out in locker rooms in high schools, in restrooms of middle schools, or on the playground of elementary schools.
Teachers can't be everywhere. There are too few parents who want to volunteer to be eyes and ears for no pay, too few students who have the courage to stand up to bullies and protest their behavior, too few with the courage to step in and protect the innocent. They have all been bullied by the fear that they will be next.
Most schools know who the bullies are, but efforts to engage the parents in behavior modification mostly prove fruitless. It's too bad that school administrators do not have the power to compel a parent to accompany their bullying son or daughter throughout the day or face expulsion. Too often, a bullying child is the product of a bullying parent and a home environment where the bullying child is himself mistreated or ignored. Since the parents are often the source of the problem, they should be forced to become part of the solution.
This would take a Judge and a Court to enforce. After expulsion, the bully could be sent to a camp for kids that are anti-social. That's what bullying is: anti-social behavior. A Boot camp for Bullys. Bully Boot Camp.
Too bad the kids often come out of a boot camp even worse than when they went in.
When a school administrator hold a meeting for parents and teachers to discuss bullying and policies and possible remedies, there are usually many parents in attendance to demand action. The parents with the bullying children are never there, are they?
I don't know what the solution is. Here, locally, at least one Middle School is contracting with the National Coalition Building Institute, a non-profit that specializes in reducing school violence, among other goals.