From a tiny closet in Mountain View, California, Sal Khan is educating the globe for free. His 1,516 videotaped mini-lectures -- on topics ranging from simple addition to vector calculus and Napoleonic campaigns-- are transforming the former hedge fund analyst into a YouTube sensation, reaping praise from even reluctant students across the world. "I think he rocks. I'm studying pre-algebra and I love it," says 11-year-old Felix Thibodeau of Wilmington, North Carolina. Derek Hoy of Australia's University of Queensland agrees, "I learned more about calculus in the last few hours than in the whole of the last semester at university." Khan envisions a world free of dense textbooks, crowded lecture halls and bored students. With 70,000 people tuning into his lectures every day, his dream seems pretty close to reality.
