Student violence in many of our nation’s schools is out of control. An Education Week teacher survey, whose results were released in March, found that 35 percent of respondents said classroom behavior was “a lot worse” than last year. It’s not just children fighting with each other; teachers are often on the receiving end of assaults. Examples of student violence against teachers are common. In southern California, as reported by the Long Beach Post in June, a Carver Elementary School teacher left school with “major purple marks” after students hit, pinched, bit, and scratched her. In an explosive moment, one...