Did you know repetition is the key to deep learning?

How many times have you read a book or an article only to not quite remember it a week later? I recently realised that I wasn’t learning as much as I thought, and found a better way to remember what I read.

Because I have trouble sleeping I read for an average of one hour while going to bed. This let’s me go through a lot of books over a year. I used to think that when I read something and had that “ah-ha!” feeling that was enough, I had learned that idea. I was wrong.

I never put any words in the feeling but believed something like whatever is important will stick. Or if I can’t remember it, maybe I’m just not that good at remembering facts? So I’d just listen to some more podcasts, watch a documentary, and read another book. I thought I “got it” and moved on. None the wiser.

A few years ago I reread one of my favourite books and was surprised by how little I remembered. Unfortunately I didn’t think more about it even then. It took me another year and getting hooked on a podcast that explained, chapter by chapter, the ideas from another favourite book for me to finally understand. I had been cheating myself out of learning all these great ideas.

When we hear about an idea and feel it “click”, that “ah-ha!” moment or insight. That is not learning. That’s just understanding. It feels great, but it’s a shallow understanding, and it doesn’t last.

To deeply learn an idea, we have to internalise it. A phrase that in this context means to make the idea a part of the toolbox of our minds. Neurologically, we’re adapting the brain to the idea. It takes time. But when it’s done the idea is there in long term memory, and you can apply it in real world situations.

Unfortunately for me, very few of the things I “learned” while reading over the last decade ever got to that level. Hell, I can’t even remember most of the ideas. Let alone apply them to anything.

Thankfully I’ve learned two ways that can help you learn deeply:


You did this in school and if you are anything like me you hated it. “Move on already, I get it…”
But how much do you remember from school? I have many times felt like I didn’t learn much at all.

Repetition works. In fact it’s crucial. Let’s explore why.

One metaphor for how the brain stores knowledge & behaviours is imagining a snowfield. With you on skies traversing over it. The first time you learn something new you pass over the snow once. The tracks you leave are shallow and easy to miss.

But if you ski those tracks 2-3 times, they deepen into ruts that are easier to find, and easier to follow.

A map looking snowy landscape with lines over it and markers.

The more repetitions, the deeper the ruts, and the easier they become to use.

This is why your school teacher forced you to do all those repetitions. And why I use Readwise to help me repeat everything new I learn today.

This metaphor is good because it also captures one of the problems with repetition. If you memorize a bad idea, or practice an unwanted behaviour, it’s hard not to slide back into those tracks. This is such a powerful side effect of repetition that it’s even used in Cognitive Behavioural Therapy to retrain irrational responses like phobias. But I digress…

Repetition of ideas specifically is hard because it’s easy to start remembering facts instead of the idea. This is how we end up with people who can endlessly retell stories and numbers, but can’t seem to relate them to anything. This is dogmatism at it’s core. They’ve learned the words, but not the idea.

The other way of learning things deeply is more useful, but also takes more effort.

Applying the idea

Just thinking about how you would apply an idea is a magical practice. Chances are high that you will realise you didn’t understand the idea as deeply as you felt you did, and struggle to use it. This almost always happens to me. That’s a good thing.

Noticing what we didn’t understand helps us learn the idea more deeply. In fact some philosophersclaim that struggling with an idea is the way we learn to understand. Let’s find a metaphor to explain why.

Another metaphor for how the brain works is Tetris. Better yet 3d Tetris. Imagine a 9x9 matrix of blocks that is your mind. And you’re trying to fit a new idea, a block in an odd shape, into that matrix. So you turn it this way or that way. Rotate it around. Sometimes it fits, but as you place the next one, you realise the first block would’ve been better placed over there.

This is similar to what we’re doing with new ideas. We’re turning it around to discover the full shape. And to figure out how it fits into what we know about the world. The more we turn it around, the more we think about how we apply it, the better we understand it.

Three dimensional Tetris pieces stacking together into a clump.

This metaphor is great because it highlights one of the truths about ideas: regardless of how many times you turn it around, you wont know how it fits until you experiment. And every time you place a block, you become better at placing similar blocks.

This metaphor also highlights one of the dangers. If you haven’t seen a lot of blocks, or don’t play around with them enough, you might start thinking they are all T-shaped…

This is why experimenting is the best way to learn ideas deeply. When we do trial and error we retain why an idea works, not just the facts that support the idea. This little piece of narrative is infinitely richer than any data-illustration of the idea.

So this weekend, instead of picking up a new book, or listening to a new podcast. Why not revisit an old one? Pick something you liked, think about the shape of the idea, and see if you can try it out!