Learning by explaining: why you understand it once you say it

A friend asks how your pension actually works. You’ve got one. You’ve read the emails. You open your mouth to explain and, two sentences in, you realise you have no idea what happens to the money between now and retirement.

That moment is awkward. It’s also one of the most useful things that can happen to your brain. Decades of research on learning by explaining show that putting an idea into words, especially for another person, is one of the most reliable ways to understand it properly. And it isn’t only for exams. It works on your opinions, your decisions and your sense of what you actually think.

Why you think you understand things better than you do

In 2002, psychologists Leonid Rozenblit and Frank Keil asked university students to rate how well they understood how everyday things work: zips, flush toilets, sewing machines. Then they asked them to write a step-by-step explanation. Then they asked for the rating again.

The ratings dropped. Once people tried to explain, they discovered their understanding was far thinner than it felt. Rozenblit and Keil called this the illusion of explanatory depth. Familiarity feels like understanding. Explaining is how you find out the difference.

What is learning by explaining?

Psychologists call the habit of talking yourself through something self-explanation. In a 1989 study, Michelene Chi and colleagues watched students learn physics from worked examples while thinking aloud. The students who did best kept explaining to themselves why each step happened and how it connected to the underlying principle. The weaker students mostly read on. That study was small (a handful of students) and only showed a link, not cause.

So in 1994 Chi’s team tested it. Fourteen eighth-graders were prompted to explain each line of a text about the circulatory system as they read it. Ten others read the same text twice. The prompted group improved more from before to after, and the students who explained the most all ended up with a correct mental model of how blood circulates.

Since then the finding has held up. A 2018 meta-analysis by Bisra and colleagues pooled 64 research reports and found that prompting people to self-explain gave a moderate, reliable boost to learning (an average effect size of 0.55), across most school subjects studied.

Does it help to explain to another person?

Here’s where it gets social. In a 2014 experiment, John Nestojko, Dung Bui, Nate Kornell and Elizabeth Bjork gave people a passage to study. Some were told they’d be tested on it. Others were told they’d have to teach it to another student. In the end nobody taught anyone; everyone took the test.

The people who expected to teach recalled more of the passage, organised what they remembered better, and answered more questions about the main points. Just picturing a listener changed how they studied.

Actually explaining does more. A 2019 meta-analysis of 28 studies in Japanese Psychological Research found that preparing to teach gave a small-to-moderate learning benefit, and preparing and then teaching gave a larger one. The benefit of teaching was bigger when it was interactive, with the learner able to respond, than when it was a one-way talk to camera.

You don’t even need an expert listener. In a 2008 study led by Bethany Rittle-Johnson, 54 four- and five-year-olds solved sorting puzzles, got feedback, and then either explained the answers to themselves, explained them to their mum, or just repeated them. Explaining helped either way, but explaining to mum led to the best results on new puzzles. The mums didn’t help. They just listened.

Researchers sometimes call this the protégé effect: in a 2009 study by Catherine Chase and colleagues, students put more effort into learning when they were teaching a computer character than when they were learning for themselves.

Why a good question beats a nodding listener

Not all explaining is equal. In 2008, Rod Roscoe and Michelene Chi studied untrained peer tutors and found many fell into “knowledge-telling”: summarising the material back without adding much. That did little for their own learning. Tutors learned most when they were “knowledge-building”: checking their own understanding, making inferences and fixing their confusions as they went.

And what often triggered knowledge-building was the other person’s questions, especially ones that asked them to work something out rather than repeat it. The friend who says “wait, but why?” isn’t interrupting your explanation. They’re the reason it works.

It works on understanding yourself too

Most of these studies used textbooks, physics problems and puzzles, not life decisions. But the mechanism is familiar to anyone who has talked something through: you only find the gaps when you have to put the thing into words for someone who can ask back.

Try explaining to a friend why you want to move cities, why that comment from your boss bothered you so much, or what you actually believe about something you argue about online. Halfway through, you’ll often hear yourself say something you didn’t know you thought. Or notice that a reason you’ve repeated for years doesn’t hold up once it’s out loud.

Try this: how to learn by explaining

1. Pick one thing you’d say you understand. A news story, a money decision, a belief you hold. Explain it out loud, step by step, as if to someone who wasn’t there.
2. Find a real listener. Ask them to stop you with “why?” and “how do you know?” whenever you skip a step.
3. Listen for the fog words. “Basically”, “sort of”, “it just does”. They usually mark a gap.
4. Check, then explain again. Look up what you were missing and give the explanation a second go. It will be shorter and clearer.
5. Swap roles. Let them explain something to you, and be the one asking good questions.

Where Everconnected fits

If you’d like to try this with someone new, Everconnected matches you with people who share your values and interests, for one-to-one conversations by voice. It’s free to join: create an account at app.everconnected.com, or get the app from the App Store or Google Play.

Questions people ask

Sources

1. Rozenblit, L., & Keil, F. (2002). The misunderstood limits of folk science: An illusion of explanatory depth. Cognitive Science, 26(5), 521-562. doi.org/10.1207/s15516709cog2605_1
2. Chi, M. T. H., Bassok, M., Lewis, M. W., Reimann, P., & Glaser, R. (1989). Self-explanations: How students study and use examples in learning to solve problems. Cognitive Science, 13(2), 145-182. doi.org/10.1207/s15516709cog1302_1
3. Chi, M. T. H., de Leeuw, N., Chiu, M.-H., & LaVancher, C. (1994). Eliciting self-explanations improves understanding. Cognitive Science, 18(3), 439-477. education.asu.edu/lcl/publications/chi-m-t-h-de-leeuw-n-chiu
4. Bisra, K., Liu, Q., Nesbit, J. C., Salimi, F., & Winne, P. H. (2018). Inducing self-explanation: A meta-analysis. Educational Psychology Review, 30(3), 703-725. doi.org/10.1007/s10648-018-9434-x
5. Nestojko, J. F., Bui, D. C., Kornell, N., & Bjork, E. L. (2014). Expecting to teach enhances learning and organization of knowledge in free recall of text passages. Memory & Cognition, 42(7), 1038-1048. doi.org/10.3758/s13421-014-0416-z
6. Kobayashi, K. (2019). Learning by preparing-to-teach and teaching: A meta-analysis. Japanese Psychological Research, 61(3), 192-203. doi.org/10.1111/jpr.12221
7. Rittle-Johnson, B., Saylor, M., & Swygert, K. E. (2008). Learning from explaining: Does it matter if mom is listening? Journal of Experimental Child Psychology, 100(3), 215-224. news.vanderbilt.edu/2008/01/23/kids-learn-more-when-mom-is-l
8. Chase, C. C., Chin, D. B., Oppezzo, M. A., & Schwartz, D. L. (2009). Teachable agents and the protégé effect: Increasing the effort towards learning. Journal of Science Education and Technology, 18(4), 334-352. purl.stanford.edu/zm369yx3532
9. Roscoe, R. D., & Chi, M. T. H. (2008). Tutor learning: The role of explaining and responding to questions. Instructional Science, 36(4), 321-350. doi.org/10.1007/s11251-007-9034-5