School shootings are at an all-time high. That's according to the National Center for Education Statistics, which has been keeping track of the numbers for about 20 years. What are schools to do? Is there a "profile" of the typical school shooter that could help us identify those who might commit a shooting in the future? Is there some combination of characteristics and circumstances that pushes people--specifically students--toward acts of extreme violence? And if these questions are unanswered or unanswerable, what can schools do instead to protect their students from these horrific incidents?