If you can’t explain something simply, you don’t understand it as well as you think you do. That’s the entire premise behind the Feynman Technique, named after physicist Richard Feynman, who was known for breaking down dense topics into explanations a child could follow. It’s not a memorization trick — it’s a diagnostic tool that shows you exactly where your understanding breaks down, so you can fix it before an exam does it for you.

The four steps

1. Write the topic at the top of a blank page. Be specific — not “thermodynamics” but “why does ice melt faster in water than in air at the same temperature.”

2. Explain it in plain language, as if teaching someone with no background. Write or speak it out loud continuously, without looking at your notes. Use simple words and short sentences. Avoid jargon — if you catch yourself using a technical term, define it in plain language too.

3. Find the gaps. You will get stuck. You’ll reach for a term you can’t actually define, skip a step because you’re not sure how it works, or realize your explanation only restates the question. Circle every one of these moments — they are the most valuable part of the exercise.

4. Go back to the source, then simplify and find an analogy. Re-read your notes or textbook only for the gaps you identified — not the whole topic. Once you understand the gap, rewrite that part of your explanation in even simpler language, and try to connect it to something you already know well.

Why this works

Explaining something forces retrieval — you have to pull the information out of memory rather than recognize it on a page, which is the same mechanism that makes active recall effective. But it goes a step further: retrieval alone tells you whether you remember something, while explanation tells you how well you understand it. You can recall a definition word-for-word and still have no idea what it means or when to apply it. The Feynman Technique exposes that gap directly.

It also overlaps with elaborative interrogation — both techniques work by forcing you to connect new information to existing knowledge in your own words, rather than storing it as an isolated fact.

A worked example

Say you’re trying to understand compound interest.

First pass explanation: “Compound interest is when you earn interest on your interest, so your money grows faster over time than with simple interest.”

That sounds fine — but try to go one level deeper: why does it grow faster, and by how much? If you can’t answer that without looking it up, you’ve found your gap.

After revisiting the source and simplifying: “Say you put $100 in an account that pays 10% interest a year. After year one, you have $110. With simple interest, you’d earn $10 again next year — always 10% of your original $100. With compound interest, you earn 10% of $110, which is $11. The next year it’s 10% of $121, and so on. The amount you earn each year keeps growing, because it’s based on a growing balance, not the original amount. Over many years, that difference compounds into a much larger gap.”

That second version is longer — but it’s the version that would survive an exam question asking you to calculate compound interest, not just define it.

Common mistakes

Jumping to an analogy too early. Analogies are useful once you understand the mechanism — but if you reach for one before you actually understand the “why,” you’ll just be memorizing the analogy instead of the concept.

Doing it in your head instead of writing or speaking it out loud. Thinking “I get this” while reading is exactly the fluency illusion this technique is designed to break. Writing or speaking forces you to produce a complete explanation, with nowhere to hide gaps.

Treating it as a one-time exercise. The first pass through a topic will reveal gaps. Revisiting your explanation a few days later — ideally on a spaced repetition schedule — often reveals new ones, because understanding settles unevenly.

How to use it today

Pick the single topic from your hardest subject that you’re least confident about. Set a timer for 10 minutes. Write the topic at the top of a page, and explain it as if to someone who has never heard of it. When you get stuck — and you will — that’s the topic to study next, not the whole chapter.

FAQ

Does this work for vocabulary or language learning, like IELTS prep? Yes, with a twist: instead of explaining a concept, explain the difference between two similar words or grammar structures (e.g., “when do I use ‘although’ vs ‘despite’?”). The gaps you find are exactly the distinctions that trip people up on exams.

How is this different from active recall? Active recall asks “can I retrieve this?” The Feynman Technique asks “can I retrieve this and explain why it’s true, in a way that would make sense to someone else?” It’s a deeper test, which is why it’s better suited to concepts than to simple facts.

Do I need someone to actually teach? No — explaining out loud to an empty room, or writing it down, works because the act of producing a complete explanation is what reveals the gaps. A real audience can help if you want feedback, but it’s not required.

For a structured way to work through gaps you find this week, spaced repetition gives you a schedule for revisiting them — and the free study kit includes a template for running both together.