So there you are, cowering under your desk.
From the hallway, you hear the pop! pop! pop! of gunfire, along with the shrieks of the terrified and moans of the dying. The good guy with a gun? Maybe he's crouched outside the building. Maybe he's dead in the break room. Whichever, he's not there. And now, horribly, the doorknob to your classroom begins to turn.
What do you do?
You throw rocks. At least, that's what you do if you're a student of the rural Blue Mountain School District in Schuylkill County, Pa. It came out last week that Superintendent David Helselhas ordered that each classroom be equipped with a bucket of river stones. "They're the right size for...