A gut-wrenching new PSA showing students protecting themselves from a shooter with their 'back-to-school essentials' calls on Americans to stop treating campus gun violence as inevitable and to educate themselves on how to prevent it. The video was released Wednesday by Sandy Hook Promise, an organization formed by the parents of children killed in the 2012 massacre that left 26 dead at Sandy Hook Elementary School in Newtown, Connecticut. By mocking classic back-to-school commercials, the PSA offers a ruthless reminder of how commonplace school shootings have become. It starts off like any other summertime school shopping ad with students showing...