AN INTERVIEW WITH SALMAN KHAN: It All Started With a 12-Year-Old Cousin. “In 2008, Salman Khan, then a young hedge-fund analyst with a master’s in computer science from M.I.T., started the Khan Academy, offering free online courses mainly in the STEM subjects — science, technology, engineering and mathematics. Today the free electronic schoolhouse reaches more than 10 million users around the world, with more than 5,000 courses, and the approach has been widely admired and copied. I spoke with Mr. Khan, 37, for more than two hours, in person and by telephone.”

My favorite bit: “I gave it try. Soon my cousins said they liked me more on YouTube than in person. They were really saying that they found my explanations more valuable when they could have them on demand and where no one would judge them. And soon many people who were not my cousins were watching. By 2008, I was reaching tens of thousands every month.”

Plus, on how Khan is different from MOOCs:

They tend to be regular courses transplanted into the virtual world. They tell you what to do in Week 1, Week 2. You take a final exam. Some people pass. Some don’t.

That’s not what we want. We don’t want to see who can keep up with an M.I.T. course and who can’t. We want to get everyone to the point that they have the knowledge that the M.I.T. course is trying to teach them. When you go to the site today, you get a test to evaluate where you are in math. You determine your own pace. And you don’t go to the next level until you’ve mastered the previous one.

Another difference between us and many of them is we have a platform where people can get personalized suggestions. Our software tracks your progress and customizes your lessons. You can take as long as necessary to get to a high level.

We’re more like a highly enriched, personalized textbook, a tool for you on your own or your teacher or tutor.

I think that’s the right direction.