LA Unified was going to spend more than $1 billion buying iPads for LA public schools. It was all about the digital divide: the idea that poor kids in public schools would fall behind, and rich kids in private schools would be better prepared for the future because they can access lots of high-tech gear. Now there’s a screen backlash. In Silicon Valley, the same tech insiders who helped make screens addictive are starting to strictly limit it for their kids. Some private schools are getting rid of screens altogether.