Sebastian Thrun left a high-powered Silicon Valley life — working in Google's secretive Google X lab, teaching about artificial intelligence and robots at Stanford — to pursue what he deemed a higher calling. Thrun started a company called Udacity, designed to "disrupt the university." His Stanford-caliber classes were online, they were free, and they were accessible to everyone. He taught to hundreds of thousands of people, instead of hundreds.

But, as Thrun tells Fast Company, there was a simple problem: people weren't finishing his classes. A study found that only seven percent of people who take a class like Udacity's actually finish, and most that do already had bachelor's degrees to begin with — free online courses have hardly been the democratizing, wide-reaching force Thrun and others had hoped for. And in this $400 billion annual market, Udacity is hardly alone; turning massive open online classes (MOOCs) into a successful education and a successful business is much harder than anyone thought.

Fast Company's Max Chafkin paints Thrun as a lover of the humanities, talking about robots in terms of human ideas and human behavior. But Udacity, Khan Academy, and universities across the world have encountered a problem that is both deeply human and deeply technical. There are solutions everywhere, but few answers so far.