The Feynman Technique
If you can't explain it simply, you don't understand it deeply enough
The Feynman Technique is a four-step learning method inspired by Nobel Prize-winning physicist Richard Feynman's approach to understanding. The core insight is devastatingly simple: complexity and jargon often mask a lack of understanding. If you can't explain something in plain language that a 12-year-old would understand, you haven't truly grasped it — you've merely memorized the vocabulary.
The technique works because it forces active recall and exposes gaps that passive reading conceals. When you sit down to explain a concept in simple terms, your brain must reconstruct the knowledge from scratch rather than simply recognizing familiar-sounding phrases. This reconstruction process is where genuine understanding lives. Every stumble, every moment where you reach for jargon because you can't find simpler words, reveals a gap in your comprehension.
The method is universally applicable — from quantum physics to business strategy to cooking technique. Feynman himself used it to demystify some of the most counter-intuitive ideas in modern physics, earning him the nickname 'The Great Explainer.' The beauty of the technique is that it serves simultaneously as a learning tool and a diagnostic tool: it tells you what you know, what you don't know, and exactly where the gaps are.
- Complexity and jargon often mask a lack of understanding — simplicity reveals mastery.
- If you can't explain it to a 12-year-old, you haven't grasped it fully.
- Writing things down forces better thinking, organizes thoughts, and reveals gaps.
- Anyone can make a subject complicated; only someone who understands can make it simple.
- The harder the subject, the more informally true experts tend to speak about it.
- Select a Concept and Map Your KnowledgeStart with a blank page and write down everything you currently know about your chosen topic. Use a different color pen for new information as you learn more over time. This creates a visual map of your growing understanding and gives you a concrete baseline to measure progress against. The act of writing forces you to confront what you actually know versus what you vaguely recognize.Pro tipUse a different colored pen each time you revisit and add to the page — watching your knowledge grow in visual layers is motivating and revealing.WarningDon't look anything up during this first step — the point is to expose what you actually know from memory, not what you can find.
- Explain It to a 12-Year-OldWrite down your understanding of the concept using only words a child would understand. No jargon, no technical terms, no acronyms. This is where most people discover they don't understand as well as they thought. If you reach for a technical term, that's a signal you're using vocabulary as a crutch instead of genuine comprehension. Writing forces better thinking, organizes your thoughts, and makes broken logic impossible to ignore.Pro tipActually read your explanation out loud — if it sounds like a textbook, you're hiding behind language rather than teaching.WarningThe temptation to use 'just one technical term' is the ego protecting your illusion of understanding. Resist it completely.
- Review, Identify Gaps, and Return to Source MaterialRead and review your simple explanation carefully. Every point where you struggled, used vague language, or couldn't find simple words marks a gap in understanding. Return to the source material and study those specific sections until you can explain them simply. Then rewrite those sections of your explanation. This iterative loop of writing, identifying weakness, studying, and rewriting is where the deepest learning occurs.Pro tipKeep a separate 'gaps list' of concepts you couldn't explain simply — these are your highest-leverage study targets.
- Test by Teaching and Archive for ReviewTest your understanding by explaining the concept to someone else without using your notes (though you can refer to them if necessary). Teaching is the ultimate test because a live audience asks unexpected questions that expose remaining blind spots. Once satisfied with your understanding, archive your simple explanation in a learning binder or digital system for periodic review, which prevents knowledge decay over time.Pro tipIf you don't have someone to teach, explain the concept out loud to an empty chair — the act of speaking engages different cognitive pathways than writing.
Richard Feynman's undergraduate physics lectures at Caltech became legendary precisely because he refused to hide behind jargon. He would explain quantum electrodynamics — one of the most complex theories in physics — using everyday language and vivid analogies. His lectures were eventually published as 'The Feynman Lectures on Physics' and remain widely used decades later.
Richard Feynman was a Nobel laureate in Physics known for his extraordinary ability to make complex ideas accessible. He won the Nobel Prize in 1965 for his work on quantum electrodynamics, but was equally famous for his teaching at Caltech, where his undergraduate lectures became legendary. Feynman's key insight was that true understanding and the ability to explain simply are the same thing — the person who hides behind jargon is the person who doesn't actually understand. Shane Parrish of Farnam Street codified Feynman's approach into four explicit steps, making the technique practicable for anyone. As Mortimer Adler noted, 'The person who says he knows what he thinks but cannot express it usually does not know what he thinks.'