The Feynman Technique: If You Can't Explain It, You Don't Know It

There's a fast way to find out whether you truly understand something or just think you do: try to explain it, simply, out loud, as if to someone who's never heard of it. The moment you start fumbling for words is the moment you've found a gap. That's the whole idea behind the Feynman technique.

The illusion of understanding

Richard Feynman, the physicist this is named after, was famous for explaining hard ideas in plain language. His insight was that fancy terminology often hides a shaky understanding — you can repeat the jargon without grasping what's underneath it.

Most of us overestimate how well we understand things, because reading and nodding along feels like comprehension. Explaining it is the test that exposes the truth.

The four steps

The technique is a short loop you repeat:

1. Study the topic as you normally would.

2. Explain it simply — out loud or on paper — in plain words, no jargon, as if teaching a curious 12-year-old.

3. Find the gaps. Wherever you stall, hand-wave, or reach for a technical term to paper over something, that's a piece you don't actually understand yet.

4. Go back and fill it in, then explain it again.

Image by Ricardo Matos via Lummi

Why it works so well

The Feynman technique quietly combines several things that learning science already knows are powerful. Explaining from memory is active recall. Putting ideas in your own words forces deep processing instead of surface memorisation. And teaching something reorganises it in your head into a structure you can actually retrieve under pressure.

In other words, it's not a gimmick — it's several proven techniques bundled into one simple habit.

Plain language is the point

The temptation is to explain things using the textbook's words. Resist it. Real understanding shows up when you can swap the jargon for everyday language and an analogy. "Entropy is disorder increasing over time, like a tidy room that drifts toward mess unless you spend energy keeping it neat" beats reciting a definition you don't feel.

If you can't find the simple words, you've found exactly what to study next.

When to use it

The Feynman technique shines on the concepts that connect things — the ones exams love to test and flashcards can't fully capture. Use it for the big ideas, the "explain the relationship between X and Y" questions, the topics you keep nodding at but never quite nail.

Final thoughts

Teaching is the highest bar of understanding, which is why "explain it simply" is one of the toughest and most honest study tools there is. Do it before the exam does it to you.

It's the exact idea behind Quzon's Grill Mode: you explain a topic in your own words, get scored on it, and then get pushed on the parts you glossed over — so the gaps show up while there's still time to fix them.