Just a few years ago, America’s public schools were rushing to get every child a laptop. Los Angeles middle school teacher Anna Soffer remembers it well: “The idea was that technology is the future, so we need to put tech in every child’s hands. ”Now, the conversation has flipped. After pouring billions of dollars into laptops, tablets and learning apps, many schools are facing a digital reckoning. Classrooms have become saturated with screens, and a growing number of parents, teachers...