The Feynman Technique
Named for physicist Richard Feynman (1918–1988), whose lectures became famous for explaining hard ideas — quantum mechanics, statistical physics, computation — in simple language. The technique distills how he learned: if you can't explain it simply, you don't understand it well enough.
What Feynman actually did
According to colleagues, Feynman kept a notebook labeled "Notebook of things I don't know about." When he wanted to understand a topic, he'd start a new section and force himself to write an explanation from scratch — no equations he couldn't justify, no terminology he couldn't unpack. Wherever he stumbled, he'd return to the source until he could write through it without choking.
The technique is that process formalized: explain → notice gaps → fill gaps → simplify until plain. It's the most demanding form of active recall, because you're producing prose, not just answering prompts.
Why it works
Three forces meet at once:
1. Retrieval — you produce the explanation from memory, the strongest form of active recall.
2. Generation — composing prose forces you to commit to a structure: what comes first, what connects, what's load-bearing.
3. Self-detection — the moments you reach for jargon or wave your hands are the gaps. They're invisible during passive reading but unmissable in explanation.
The four steps
Choose a concept
Write the concept name at the top of a blank page. One specific concept — not a chapter. "How does compounding work" beats "finance."
Explain in plain language
Write a full explanation as if for someone with zero background. No jargon. Use analogies, short sentences, concrete examples. Aloud is best.
Identify gaps
Mark every place you waved your hands, reached for a term you couldn't unpack, or said "kind of." Those are your gaps — the real syllabus.
Refine & simplify
Go back to the source for each gap. Rewrite the explanation. Repeat until a smart non-specialist would follow it. Done is "no hand-waving left."
The Feynman workbench
Jargon spotter
Paste any explanation you wrote. The spotter highlights overly-academic terms that signal hand-waving — common Feynman red flags. Aim for an explanation a smart 12-year-old could follow.
Three worked examples
Entropy
From "measure of disorder in a system" to "shuffled cards never sort themselves" — the four steps applied to a physics concept undergrads usually parrot without understanding.
Opportunity cost
From the textbook definition to "what the next-best thing was that you didn't pick." Where students slip and how Feynman would have caught it.
Recursion
From "a function that calls itself" to a Russian-doll story. Plus the load-bearing detail — the base case — most students hand-wave over.
Connect the dots
Quiz
15 questions on the Feynman Technique.
Flashcards
Tap to flip. Twenty essential terms.
Teacher mode
Lesson outline, evaluation rubric, and a printable worksheet.
Lesson outline (45 min)
- 5 min · Hook — Pick a term from this week's content. Ask: "Who can explain X to a 6th-grader, right now, no prep?" Watch the room. Land the point: recognition isn't understanding.
- 10 min · Concept — Feynman's notebook habit. Why generation beats recognition. The 4 steps.
- 5 min · Demo — Walk one worked example (entropy / opportunity cost / recursion) on the board, voicing the gaps as they appear.
- 20 min · Practice — Each student picks a concept from current material and does one full pass on paper. Pair up; explain to your partner; mark each other's hand-waves.
- 5 min · Wrap — Identify the top three "gap" terms across the class. Re-teach those tomorrow.