In the six minutes before someone phones 911 to report a mass shooting, six people will die. The shooter could hit another dozen victims before the cops arrive. That’s what John Benner, a retired SWAT commander in Ohio, impresses upon teachers learning to wield firearms along with their dry-erase markers. The debate over guns in the classroom has raged as the school toll mounts, but an untold number of teachers are already packing. Going through Benner’s training scenarios, however, they discover that the kids they shoot aren’t always the bad guys.