CBS

Sal Khan teaches math, science, and history to millions of students, but none has ever seen his face.

Khan is the voice and brains behind the Khan Academy--a free online tutoring site that was born out of a young cousin's struggles with algebra in 1994. His classroom has grown from a few hundred pupils to more than 4 million a month.

Khan, 35, believes he can transform education worldwide, and his approach is now being tested in American schools. Along the way, the former hedge fund analyst has won the support of Google Chairman Eric Schmidt and Microsoft co-founder Bill Gates, who calls Khan "a teacher of the world."

He has since founded a nonprofit with a simple but ambitious goal: "to provide a free, world-class education for anyone, anywhere." CBS' news magazine "60 Minutes" (see segment video below) caught up with Khan at his startup's tiny office, located above a tea shop in Silicon Valley.

It all began when he agreed to remotely tutor his cousin Nadia, a seventh-grader in New Orleans, with her algebra. He recorded the 15-minute lessons and posted them to YouTube. They proved helpful to Nadia--and to total strangers who stumbled upon them and sent him letters.

"I started getting feedback like, 'You know, my child has dyslexia, and this is the only thing that's getting into him'," he said. So in 2009, he quit his job to devote himself to the academy full time.

Since the effort's humble beginnings eight years ago, Khan, who has three degrees from MIT and an MBA from Harvard, has recorded and uploaded 3,000 lessons. Now, thanks to more than $15 million in funding from Google and Gates--who was using the free tutorials to teach his own children--Khan has hired engineers and designers to develop a software platform he hopes will change the way math is taught.

One of the fruits of Khan's labors is a free iPad app that was published today to the iTunes Store, offering free access to the academy's full library of lessons.

Will Khan's approach to integrate technology into education succeed where so many other efforts have failed? Google's Schmidt is optimistic and says he sees promise with Khan's approach.

"Innovation never comes from the established institutions," Schmidt says. "It's always a graduate student or a crazy person or somebody with a great vision. Sal is that person in education in my view.

"He built a platform. If that platform works, that platform could completely change education in America."

The full segment: