WHEN twelve students and a teacher were shot dead in the Columbine High School massacre, public alarm (abetted by the media) was inevitable. In a Newsweek poll immediately following the killing, 63 percent of Americans said that it was “very or somewhat likely that a shooting incident could happen in their schools.” In fact, however, such shootings remain rare—and thus newsworthy. Fewer than 1 percent of homicides involving school-age children actually occur in or near schools, according to the Centers for Disease Control. When kids are killed, it’s almost always elsewhere.  “Have you ever ... had a weapon such as a gun or knife, pulled on you at school?” California students were asked in a 1998 survey. Only 2 percent answered yes.