The Feynman Technique, With Real Before-and-After Examples

The Feynman technique is a four-step way to test your understanding: explain a concept in plain words as if to a 12-year-old, notice where the explanation stumbles, go back to the source to fix those gaps, then simplify again. The examples below show it applied to compound interest, why bread rises, and the causes of the 1929 stock market crash, so you can see what a weak explanation looks like next to a strong one.

The method is named after the physicist Richard Feynman, who was famous for explaining hard physics without jargon. You can read his own teaching style in the free Feynman Lectures on Physics hosted by Caltech. The four-step recipe itself is a later summary of his approach, not something he wrote down as a formula, but it captures the core idea well: if you cannot say it simply, you probably do not understand it yet.

The four steps in one minute

1. Name the concept. Write it at the top of a blank page. Keep it narrow: “how a mortgage amortizes”, not “personal finance”.
2. Explain it to a beginner. Write or say the explanation as if to a bright 12-year-old. No jargon unless you define it in the same sentence.
3. Find the gaps. Circle every spot where you hand-waved, used a technical word as a crutch, or wrote “basically” before something vague.
4. Return, repair, simplify. Go back to the source for each gap, then rewrite the explanation shorter and add one concrete analogy or example.

The value is in step 3. Writing an explanation forces you to produce the idea from memory, which is a form of the active recall that sits at the center of most study methods that actually work.

Example 1: compound interest (personal finance)

First attempt

“Compound interest is when your interest earns interest, so your money grows exponentially over time thanks to compounding.”

Read it as a 12-year-old would. “Exponentially” and “compounding” are doing all the work, and the second one is the word being defined. The explanation is circular.

Gaps found

• What does “interest earns interest” actually look like in numbers?
• Why does it speed up instead of growing by the same amount each year?
• What makes it grow faster or slower?

Repaired version

“Say you put $100 in an account that pays 10% a year. After one year the bank adds $10, so you have $110. In year two it pays 10% of $110, which is $11, not $10. The extra dollar is interest paid on last year’s interest. Each year the pile is bigger, so each year’s 10% is bigger. That is why the growth starts slow and speeds up. A higher rate or more years makes the effect much stronger.”

Notice the change: a specific number, a step you can check with a calculator, and a plain reason for the speed-up. The explanation is longer, but every sentence carries weight.

Example 2: why bread rises (cooking)

First attempt

“Yeast ferments the dough and makes it rise. You knead it to develop the gluten.”

This is a recipe, not an explanation. “Ferments” and “develop the gluten” are labels. A beginner would still not know why under-kneaded bread comes out dense.

Repaired version

“Yeast are tiny living things that eat sugar from the flour and give off carbon dioxide gas. On its own the gas would just escape. Kneading stretches proteins in the flour into a stretchy net, a bit like a balloon wall. The gas gets trapped in that net in thousands of small bubbles, and the dough puffs up. Heat in the oven makes the bubbles expand once more and then sets the net firm. If the net is weak, the gas escapes and you get a dense loaf.”

The balloon analogy does the heavy lifting, and it immediately predicts a practical outcome. A good Feynman explanation usually lets you predict something you were not told.

Example 3: the 1929 crash (history)

History is where people most often mistake a list of facts for understanding.

First attempt

“The 1929 crash was caused by speculation, buying on margin, overproduction and bank failures.”

Four causes, zero connections. Ask “how did one lead to the next?” and the explanation collapses.

Repaired version

“In the late 1920s many people bought shares with borrowed money, putting down a small part of the price and borrowing the rest. That works while prices rise. When prices started falling, lenders demanded their money back, so borrowers had to sell, which pushed prices down further, which forced more selling. It was a chain reaction. Prices had also climbed far above what companies were really earning, so there was a long way to fall.”

The repaired version is a causal story with a feedback loop. Writing it showed where the knowledge was thin: the role of the banks is still missing, which tells you exactly what to read next.

Signs your explanation is still weak

• You used the term you are defining, or a near-synonym of it.
• A sentence contains “basically”, “sort of”, or “kind of” in front of the key idea.
• You listed parts without saying how they connect.
• You could not give a concrete example with real numbers or objects.
• Your explanation would not let a beginner predict anything.
• You needed to glance at notes to keep going.

How to fit it into a busy week

A full Feynman pass on one narrow concept takes 15 to 25 minutes. You do not need to do it for everything. Use it on the two or three ideas per week that the rest of your material depends on. Say you are working through a beginner chess course: the concept of “tempo” might deserve a Feynman pass, while the names of the pieces do not. (If chess is your project, see learning chess as an adult for a full plan.)

Day	Time	Feynman task
Monday	20 min	First written explanation of this week’s core concept
Tuesday	10 min	Read source material only for the circled gaps
Wednesday	10 min	Rewrite shorter, add an analogy
Friday	5 min	Say it aloud from memory, no notes; record on your phone
Next week	5 min	Explain it again cold before starting the new concept

The Friday and next-week repeats add spacing, which helps the explanation survive. Pair it with a memory palace when the concept rests on a few arbitrary facts you also need to hold.

Common mistakes

• Picking topics that are too big. “Economics” cannot be Feynmaned. “Why a price ceiling causes shortages” can.
• Explaining in your head. Silent explanations skip the hard parts. Write or speak out loud.
• Dumbing down instead of simplifying. Simple means fewer words between the reader and the idea, not leaving out the mechanism.
• Skipping step 4. Finding gaps without going back to the source just leaves you with a list of things you do not know.
• Never using a real audience. Writing for an imaginary child is useful, but a real listener asks questions you would never think of. That step up is covered in learning by teaching others.

Free tools that help

• A blank sheet of paper. Still the best tool: no autocomplete, no copy-paste.
• A voice memo app. Speaking exposes stumbles faster than typing.
• Index cards. Write the concept on the front and a three-sentence explanation on the back for later review.
• A readability checker such as the one built into many word processors, to catch jargon-heavy sentences.

Where to go next

Choose one concept from whatever you are learning right now and run it through the four steps today, in writing, in under 20 minutes. Keep the first attempt so you can compare it with the final version; the difference is often the most motivating thing you will see all week. Then fit Feynman passes into a broader routine using the morning learning routine guide or your existing study slot.

Frequently asked questions

What is an example of the Feynman technique?

Explaining compound interest is a classic one. A weak first attempt says "interest earns interest, so money grows exponentially", which just repeats the term. The repaired version uses numbers: $100 at 10% becomes $110, then year two pays $11 because the 10% now applies to $110. Finding and fixing that circular first draft is the whole technique in miniature.

What are the 4 steps of the Feynman technique?

First, choose a narrow concept and write it at the top of a page. Second, explain it in plain language as if to a 12-year-old. Third, mark every place your explanation is vague, circular or relies on jargon. Fourth, return to your source to fill those gaps, then rewrite the explanation more simply with a concrete example or analogy.

Does the Feynman technique actually work?

It draws on two well-supported learning effects: retrieving information from memory and explaining ideas in your own words, both of which tend to improve understanding and retention compared with rereading. There is little research on the exact four-step recipe itself, but its ingredients are sound. It works best for concepts and processes rather than lists of arbitrary facts.

How long does the Feynman technique take?

A full pass on one narrow concept usually takes 15 to 25 minutes: about 10 minutes for the first explanation, 5 to 10 for checking gaps against the source, and a few minutes to rewrite. Short repeat explanations a few days later take under 5 minutes each and help the understanding stick.

Can you use the Feynman technique for math?

Yes, and it is especially useful for the "why" behind a method. Explain why a formula works or why a step is allowed, using a small numeric example you can check. If your explanation only lists the steps, you have memorized a procedure rather than understood it. Pair Feynman explanations with plenty of mixed practice problems.

Is the Feynman technique good for adults over 40?

It suits older learners well, because adults usually have plenty of real-world experience to draw analogies from, and analogies are what make Feynman explanations click. Keep sessions short, write rather than think silently, and revisit each explanation a few days later. Nothing about the method gets harder with age.

Do I need any tools for the Feynman technique?

No. A blank sheet of paper and a pen are ideal because they stop you from copying text. A voice memo app on your phone is a useful extra: recording yourself explaining a concept out loud makes hesitations and vague phrases easy to spot when you play it back.

Continue in this guideStudy Methods That Actually Work for Busy Adults →

This article was drafted with AI assistance and reviewed by the Life Learning Journey editorial team. Read our editorial standards.