It’s 11 pm and across South Korea the cram schools are finally set to close. For millions of bleary-eyed teenagers it’s the welcome end of a 15 hour school day. Next morning in the first lesson, exhausted students fall asleep at their desks. Sep 6, 2017. "Personalized learning" has become one of the most highly praised styles of instruction in Silicon Valley. New evidence suggests the endorsements hold water. She…