Psychologists are quickly learning how dangerous smartphones can be for teenage brains. Research has found that an eighth-grader's risk for depression jumps 27% when he or she frequently uses social media. Kids who use their phones for at least three hours a day are much more likely to be suicidal. And recent research has found the teen suicide rate in the US now eclipses the homicide rate, with smartphones as the driving force. But the writing about smartphone risk may have been on the wall for roughly a decade, according to educators Joe Clement and Matt Miles, coauthors of the recent book "Screen Schooled: Two Veteran Teachers Expose How Technology Overuse is Making Our Kids Dumber." It should be telling, Clement and Miles argue, that the two biggest tech figures in recent history - Bill Gates and Steve Jobs - seldom let their kids play with the very products they helped create. "What is it these wealthy tech executives know about their own products that their consumers don't?" the authors wrote. The answer, according to a growing body of evidence, is the addictive power of digital technology. Gates, the former CEO of Microsoft ... didn't let his kids get cell phones until they turned 14. Jobs, who was the CEO of Apple until his death in 2012 ... prohibited his kids from using the newly-released iPad. "It's interesting to think that in a modern public school, where kids are being required to use electronic devices like iPads," the authors wrote, "Steve Jobs's kids would be some of the only kids opted out."