The Feynman technique: 4 steps, an example and the research

The Feynman technique is a way to learn something by explaining it in plain words, as if to someone who knows nothing about the subject. You pick a concept, explain it simply, notice where your explanation breaks down, go back to the source to fill those gaps, and then simplify again. The places where you get stuck show you exactly what you don't understand yet.

It's named after Richard Feynman, the physicist who won the Nobel Prize in 1965 and was known for explaining hard ideas simply. This post covers the four steps, one example followed all the way through, and what research says about why explaining works.

The 4 steps of the Feynman technique

Guides word the steps a little differently, but they share the same four:

1. Pick a concept. Write its name at the top of a blank page. Keep it small enough to explain on one or two pages, like "compound interest" rather than "personal finance".
2. Explain it in plain words. Write or say an explanation for someone with no background, without looking at your notes. Farnam Street's guide puts the listener at 12 years old. Use short words and no jargon.
3. Find the gaps and go back to the source. Mark every place where you got stuck, used a term you couldn't define, or skipped a step with "and then it just works". Reread the book, article or lecture for those parts, then explain them again.
4. Simplify and use an analogy. Cut your explanation down until each sentence is clear, and replace the hardest part with a comparison of your own.

Then check it. Explain the concept to a real person, or come back a few days later and explain it again from memory.

A Feynman technique example, start to finish

Say you've just read an article about compound interest and want to understand it.

Step 1. You write "Compound interest" at the top of the page.

Step 2. You explain it without notes: "When you save money, the bank pays you interest. With compound interest, you also get interest on your interest, so your money grows faster over time." Then you try to explain why it grows faster, and the explanation stops. You can't say how much faster, or why the growth speeds up instead of staying steady.

Step 3. You go back to the article and find the missing part. In year one, $1,000 at 5% earns $50. In year two, the interest is 5% of $1,050, which is $52.50. Each year's interest is a little bigger than the last, because it's calculated on a bigger amount. You add that to your explanation.

Step 4. You simplify it and find an analogy: "Compound interest is like a snowball rolling downhill. It picks up snow, and the bigger it gets, the more snow it picks up each turn." Your final explanation fits in four sentences, with the snowball and the $1,000 example.

When you explain it to a friend, they ask "so does it matter when I start saving?" You realize you can answer that now: starting earlier gives the snowball more turns. That question would have stopped you at step 2.

Why explaining helps you learn

There's no study of "the Feynman technique" under that name, but there is research on its parts.

In a study published in Applied Cognitive Psychology in 2018, Aloysius Wei Lun Koh and colleagues had 124 students study a text on the Doppler effect. Some then taught it to a camera without notes, some taught from a script, and some wrote down everything they remembered. A week later, in a surprise test, the students who taught without notes did better than those who taught from a script, and about as well as those who wrote down what they remembered. The authors concluded the benefit of teaching comes from retrieval practice: pulling the ideas out of your own memory.

That points to the part of the Feynman technique that matters most: explaining from memory. Explaining with your notes open feels productive, but in that study reading from a script didn't help.

Self-explanation, where you explain to yourself how a new idea works or how it connects to what you know, is one of the ten techniques John Dunlosky and colleagues reviewed in 2013. They rated it moderate, below practice testing and spacing practice out over time, which got the highest rating.

Where the Feynman technique came from

Feynman didn't name the technique himself. The four-step version you'll find online was put together long after his death in 1988, from stories about how he studied. The best known is from James Gleick's biography Genius: before his oral exams at Princeton, Feynman started a notebook titled "Notebook Of Things I Don't Know About" and rebuilt each area of physics in it from the basics.

The method as a numbered list seems to have spread through learning blogs around 2011, with Scott Young's writing often named as the first. Feynman's habits are real. The tidy four steps are a later summary of them.

When the Feynman technique doesn't fit

The technique is built for ideas you need to understand, like how something works or why something happens. It's slow, so it's a poor fit for things you only need to recall, like vocabulary, dates or the steps of a procedure. For those, flashcards with active recall work faster.

It also doesn't keep the idea in your head on its own. One good explanation today fades like anything else, as the forgetting curve shows. Come back and explain the concept again a few days later, then a few weeks later. That's spaced repetition applied to explanations.

Using the Feynman technique on what you read

You can use the Feynman technique on any article or book chapter. When you finish reading, close it and write three or four sentences on the main idea, as you would explain it to a friend. Wherever you get stuck, go back to that part of the text. If you keep notes in a commonplace book, keep your plain-words explanation there too.

I made Bundle to do the "close it and explain" step after every article you save. At the end of each article a Quick check asks you a few questions about it, and you answer from memory before you look. You keep the good questions as cards, and Bundle brings each one back with spaced repetition, a little before you'd forget it.

QUICK CHECK · SCIENCE Which night of sleep matters most after you study? The night after. It is at least as important as the night before, because that sleep cements what you learned. Sleep On It: How Snoozing Strengthens MemoriesShow in article

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Questions about the Feynman technique

What are the 4 steps of the Feynman technique?

Pick a concept, explain it in plain words without notes, go back to the source wherever you got stuck, and simplify your explanation with an analogy of your own.

Do I need another person for the Feynman technique?

No. You can write the explanation or say it out loud to yourself. A real listener helps, because their questions show gaps you didn't notice.

Is the Feynman technique good for exams?

It's good for subjects where you need to understand and apply ideas, like science, economics and math. For memorizing facts, use flashcards and practice tests alongside it.

How long does the Feynman technique take?

For one small concept, expect anywhere from 20 minutes to an hour, longer if you need to reread a lot. That's why it works best on the few ideas that matter most in a book or a course.