“Mass shootings have been occurring more frequently in recent years, an FBI study shows, with nearly one incident a month from 2000 to 2013.”

“Expecting educators to plan a counterattack against an armed intruder is unrealistic, he added. ‘Cops don’t think like teachers, and teachers don’t think like cops,’ he said.”

“School officials and security experts say that the lockdowns are a modest and sensible effort to guard against the unthinkable, and that they have helped keep students safe, calm and organized during shootings and emergencies. And dozens of times every month, the drills become reality.”

“For students across the country, lockdowns have become a fixture of the school day, the duck-and-cover drills for a generation growing up in the shadow of Columbine High School in Colorado and Sandy Hook Elementary School in Connecticut.”