The battle over America's classrooms -- featuring broom-wielding reformers pitted against long-powerful teacher's unions -- has created a firestorm of debate around the question of how best to educate students and prepare them for the 21st Century. Sitting on the sidelines of this battle -- however quietly, for now -- is a man named Sal Khan. A one-time hedge fund analyst, Khan has become an unlikely hero in education circles for his innovative methodology, one that turns the classroom dynamic upside down.