22. Sal Khan: “If It Works for 15 Cousins, It Could Work for a Billion People.”

Khan Academy grew out of Sal Khan’s online math tutorials for his extended family. It’s now a platform used by more than 115 million people in 190 countries. So what does Khan want to do next? How about reinventing in-school learning, too? Find out why Steve nearly moved to Silicon Valley to be part of Khan's latest venture.