The Feynman technique: learn a topic by explaining it simply

What the Feynman technique is

The Feynman technique is a way to learn something by explaining it in simple words, as if to someone who has never studied it. Wherever your explanation gets vague, jumps a step or falls back on jargon, you've found a gap in your understanding. You go back to your notes, fix the gap, and explain it again until the explanation holds up.

It's named after Richard Feynman, the physicist who shared the 1965 Nobel Prize in Physics for work in quantum electrodynamics (Nobel Prize) and was known for explaining hard ideas plainly. The four-step version below is a popular summary that carries his name, not a procedure from a study. The idea behind it, though, has solid research support.

Why explaining works

Most of us think we understand things better than we do. Psychologists call this the illusion of explanatory depth. In a series of studies, people rated how well they understood everyday devices, such as a zipper, then tried to write out a step-by-step explanation. Their confidence dropped once they tried. The researchers found the illusion is far stronger for explanatory knowledge, how things work, than for facts or procedures (Rozenblit & Keil, 2002). Explaining is how you find out.

Explaining also helps you learn, not just test yourself. In a classic study, eighth-grade students read a text on the human circulatory system. Those who were prompted to explain each line to themselves gained more from pretest to posttest than students who read the text twice, and the students who produced the most explanations built the most accurate picture of how the system works (Chi et al., 1994). A meta-analysis of 64 research reports on self-explanation prompts found an overall weighted mean effect size of g = .55 (Bisra et al., 2018).

The Feynman technique, step by step

1. 1Pick one concept. Narrow is better: "how blood pressure is measured", not "the cardiovascular system".
2. 2Explain it in plain words, without your notes. Write it down or say it out loud, as if to a curious 12-year-old. No jargon unless you define it.
3. 3Find the gaps. Underline every place you got stuck, waved your hands ("and then it just works") or used a term you couldn't define.
4. 4Go back to your notes for those gaps only. Read the exact part you need, then close the notes again.
5. 5Explain it again, simpler. Use an analogy or example if it helps. Repeat until the explanation runs start to finish without a stumble.

A worked example: blood pressure

First attempt

"Blood pressure is how hard your blood pushes. It's two numbers, like 120 over 80. The doctor measures it with the cuff thing. High blood pressure is bad."

Finding the gaps

• "How hard your blood pushes" against what?
• Why two numbers? What does each one mean?
• What does the cuff actually do?
• What are the units?

Back to the notes

Your lecture note says blood pressure is the pressure of blood against the artery walls, written as systolic over diastolic in mmHg. Systolic is the pressure when the ventricles contract and push blood out. Diastolic is the pressure while the heart relaxes between beats. It's measured with an inflatable cuff around the upper arm.

Second attempt

"Your heart pumps in beats. Each time it squeezes, blood is pushed into your arteries and the pressure on their walls goes up. Between beats, the heart relaxes and the pressure drops, but not to zero. Blood pressure records both: the high point when the heart squeezes (systolic) and the low point when it relaxes (diastolic). So 120/80 means 120 at the squeeze and 80 between beats, measured in millimetres of mercury. A cuff around your arm is inflated and slowly let down, and the reading is taken from the pressure in the cuff."

The second version is longer, but every sentence can be checked, and you can now see the next gap: how exactly the cuff reading tells you each number. That's your next round.

Check your explanation against your notes

A simple explanation can be simple and wrong. Analogies are where errors hide, because they stretch further than the thing they describe. After your final version, check it line by line:

1. 1Mark every factual claim in your explanation.
2. 2Find the line in your notes or textbook that supports each one.
3. 3If you can't find support, either look it up in a reliable source or cut the claim.
4. 4Note where your analogy breaks down, so you don't carry the mistake into the exam.

This also shows you the limit of your notes. If the explanation needs a fact your notes don't have, add it now, with its source.

When to use it, and when not to

The technique suits mechanisms and processes: how something works, why something happens, how two ideas relate. That makes it a good fit for physiology, economics, chemistry and law. It's less useful for pure memorisation, like drug names or dates, where flashcards and self-testing do the job better. For those, see how to study from your own notes before an exam.

It also pairs well with a study partner. Take turns explaining a topic, and have the listener ask "why?" until the explainer gets stuck.

Using an AI notes app for the checking step

The checking step is where a notes app can help, as long as it comes after your own attempt. With Lumyo, you choose the notes for a course and ask about the claim you're unsure of. The answer cites the notes it used, and tapping a source opens the exact line, so you can compare it with your explanation. If your notes don't cover the claim, it says so instead of guessing, which tells you where to look next.