Richard Feynman

I recently mentioned that I love the Khan Academy, but I didn’t explain why.

Salman Khan, the principal behind the Khan Academy material, understands something very important that emanates throughout all of his lectures whether they be on calculus, projectile motion, or thermodynamics: There is a difference between knowing the name of something and knowing something. When Sal explains a concept he focuses on why it is what it is, not just what it is. When explaining a mathematical formula he tells you why it is so, and how you can derive the same with some fundamental knowledge, a little intuition, and deductive reasoning.

An example: When Sal explains how to find the change in distance over time in projectile motion physics he doesn’t focus on which previously prescribed formula is appropriate, but how you can always figure out what to do using the cardinal rule, d = v * t, and some common sense. Khan wants you to learn how everything fits together, not whether there’s a minus or square root in one or another exotic equation that he bestows upon you.

Salman reminds me of the father Richard Feynman described in his book, What Do You Care What Other People Think?:

The next Monday, when the fathers were all back at work, we kids were playing in a field. One kid says to me, “See that bird? What kind of bird is that?” I said, “I haven’t the slightest idea what kind of a bird it is.” He says, “It’s a brown-throated thrush. Your father doesn’t teach you anything!” But it was the opposite. He had already taught me: “See that bird?” he says. “It’s a Spencer’s warbler.” (I knew he didn’t know the real name.) “Well, in Italian, it’s a Chutto Lapittida. In Portuguese, it’s a Bom da Peida. In Chinese, it’s a Chung-long-tah, and in Japanese, it’s a Katano Tekeda. You can know the name of that bird in all the languages of the world, but when you’re finished, you’ll know absolutely nothing whatever about the bird. You’ll only know about humans in different places, and what they call the bird. So let’s look at the bird and see what it’s doing—that’s what counts.” (I learned very early the difference between knowing the name of something and knowing something.)

You can know all of the mathematical formulae in the world, or all the abstract concepts, but if you don’t understand why they are as they are, and how they fit together, you’re not going to get very far. I’m sure every teacher tries to convey this, but Khan puts them to shame. By focusing on the relationships between all of the topics he discusses he invokes an ever-repeating sense of “just getting it” — and that’s what really matters, not memorizing a bunch of equations for your exams.

I’m glad that thousands of people, rather than just a single classroom, enjoy his teachings every minute.