What is the source for Feynman describes the learning technique named by his name?

Question

There is a lerning technique by Richard Feynman, which is known as "Feynman learning technique", and consists of four steps:

1. Select a concept to learn.
2. Teach it to a child. (Or maybe an adult who have zero knowledge in that field.)
3. Identify gaps in your explanation. Go back to the source material to better understand it.
4. Organize and simplify.

You can find its description, for example, here or here.

But where can I find its original description, that is, the description provided by Richard Feynman himself?

Answer 1

As noted by Bryan, Feynman didn't coin this technique. It was developed by Scott Young (see the comments section here - https://www.scotthyoung.com/blog/2011/09/01/learn-faster/) and named in honour of Feynman:

The technique is loosely inspired by an account in Richard Feynman's biography about understanding the Yang-Mills mass gap. But he didn't follow the exact structure I'm doing (explaining as if teaching it to someone else), his was more like a close reading. So in that sense, the technique is mine (although, self-explanations have a long tradition in educational psychology as well, so I can't take credit for the overall concept).

I've read Feynman's autobiography and several of his lecture series. If he had any educational philosophy, it's probably best encapsulated in this quote from his biography: "We must remove the rigidity of thought... We must leave freedom for the mind to wander about in trying to solve the problems... The successful user of mathematics is practically an inventor of new ways of obtaining answers in given situations. Even if the ways are well known, it is usually much easier for him to invent his own way - a new way or an old way - than it is to try to find it by looking it up."