Right now, public schools have their hands tied about what they can do with bullies. Every child is guaranteed the right to a public education, so even if a child is a bully, and is harming other students through physical, or mental acts of bullying, the child can not be kicked out of the school.
We need to empower schools, and school districts, to remove disruptive students not only from the schools, but from public schools in general. I dangerous student should have no "right" to attend, and they and their parents should be held responsible to find alternative means of education that doesn't put other children's well-being at risk.
This would also have the added benefit of allowing teachers to teach, by removing particularly disruptive and dangerous students.