Feynman
Technique
You read the chapter twice. You highlight the key lines, nod along, close the book feeling ready. The next day a friend asks you to explain it, and you go blank.
What is the Feynman Technique?
The Feynman Technique is a learning tool that tests your understanding by making you explain a topic in plain language, as if teaching it to a child. You pick one concept, write an explanation in simple words with no jargon, and watch for the moments you stumble or reach for a technical term you can't unpack. Those moments are the gaps in your understanding. You return to the source, fill each gap, and explain again until the whole thing is clear and simple. The technique is named after the physicist Richard Feynman, known for explaining hard ideas in plain terms.
Rereading and highlighting feel like learning, yet they mostly build a sense of familiarity, not real understanding. Explaining is harder, because plain words leave nowhere to hide: the instant you can't put an idea simply, you've found the exact spot you don't truly grasp. That discomfort is the value, since it points you straight to what needs more work.
How to use it
Run a concept through five steps. A blank page and honesty about your own blank spots are all you need.
- Choose one concept and write its name at the top of a page.
Keep it to a single idea, not a whole subject. - Explain it in plain words, as if to a twelve-year-old.
Write full sentences in everyday language. No jargon, no copying the textbook's phrasing. - Find where you get stuck.
The places you stumble, wave your hands, or fall back on a term you can't define are your gaps. Mark each one. - Go back to the source and relearn those parts.
Read, ask, or look it up until you can explain the stuck part simply. - Rewrite it simply and add an analogy.
Tie the idea to something familiar, and revise until a beginner could follow it start to finish.
Worked example
You want to understand compound interest. You write a plain explanation: "Money in a savings account earns interest, and the next year you earn interest on your original money plus last year's interest, so it grows faster the longer you leave it." Then you hit a wall trying to say why it grows faster than plain interest, and the hand-waving tells you that's your gap.
You look it up and learn the key point: the interest itself starts earning interest, so the growing total feeds its own growth. You add an analogy: a snowball rolling downhill picks up more snow each turn because it's already bigger from the last turn. Now you can explain compound interest to anyone in under a minute, which means you finally understand it rather than just recognize the words.