Thomas Sojka

100 Days of Spaced Repetition

100 days ago I was introduced to Spaced Repetition, a learning method scientifically proven to work. The basic idea is to learn facts and repeat them at increasing intervals. After several iterations, you remember the fact forever.


I was introduced to Spaced Repetition by reading How To Remember Anything Forever-ish by Nicky Case. It is a great introduction because you will begin your Spaced Repetition adventure while you are still reading. After you finish the article you will know what Spaced Repetition is, how it works, why it works and you will have completed your first session.

In this article, I want to share my experience 100 days after reading the article and I can say this much in advance: you really should try it yourself.

Why I thought Spaced Repetition is a bad idea 🤔

Although I immediately started with Spaced Repetition after reading the article, I had some doubts about whether it was really useful. There is simply no need to memorize everything when you have a smartphone in your pocket with all possible facts only fingertips away. Still, I wanted to try it for a few weeks, learning 10 facts a day. This was enough to change my mind.

Which benefits changed my mind 🤯

Staying in the flow ⌛

I work as a programmer and need to remember many function names. With Spaced repetition instead of opening a browser and google for a function name, I can create a new fact each time I forget one. After some time I can stay in the flow of my current work for a long time.

Besides function names, other things interrupt my workflow, such as forgetting mathematical conversions or having to recalculate constants (e.g. how many seconds are in a day). I am sure that in every profession there is some information that you constantly recheck and getting rid of this is a soothing experience.

Keep valuable knowledge 🗝️

Before I did Spaced Repetition I felt that all that mattered was knowing where to find information and that keeping it all in your memory was bad because of limited memory space. I still think that for some information it is bad to keep them in your memory, e.g. unfinished tasks that you are afraid of forgetting should be written down immediately because a lot of stress vanishes when you note them down. But while it's stressful to keep certain information in your brain, I no longer feel like memory space is limited in any way. As long as you memorize new things at a steady and fairly slow pace, it feels like you can go on forever.

I also noticed another change. Whenever I read something, I am constantly searching for relevant facts I can use for Spaced Repetition in the back of my mind. This makes my readings more valuable because I can be sure not to forget anything important and scanning texts for relevant facts helps me to better understand the text itself.

Think outside the box 📦

There are some topics that I deem important to know but have always been too lazy to learn. For example, how my country's political system works, understanding the effects of global warming in concrete numbers, or current relevant events like understanding how the Covid-19 vaccine works.

These topics or pretty much any topic where I have no prior knowledge or forgotten everything I learned in school would have been intimidating to learn for me. Now, with Spaced Repetition I can learn those topics slowly e.g. by starting with three definitions about the topic and building up upon those facts which seems less scary to me. Learning new subjects slowly is much easier for me and I take pride in acquiring the knowledge I think is important.

What surprised me in the last 100 days 😮

My daily recap time is not constantly increasing. I expected that as I added more facts per day, it would take me more and more time to recap my facts. But currently it takes me about 15-20 minutes each day and it's not getting any longer.

Boring facts are hard to remember. Whenever I have trouble remembering a fact, I realize that the fact is not interesting to me anymore. It's really important to add facts that interest you to facilitate learning.

One thing which was frustrating at times was finding the material for my 10 daily facts. This struggle felt like a constant rollercoaster, in the beginning, it was easy and sometimes I would prepare more than 10 facts and be able to save them for the next day. Other days, I would spend 40 minutes and end up with new facts that I wasn't interested in. I am confident I will improve and hopefully my blog post "A Year of Spaced Repetition" will be full of good advice on how to find facts that are relevant to you.

Another surprise was my renewed interest in old topics which had not interested me for a while. I studied information systems, which is a mixture of computer science and economics, but after university, I became completely immersed in programming and haven't learned anything related to economics in years. With Spaced Repetition, it was easy to get back into it because I could relearn it in small steps, which was is a nice experience.

At the end of How To Remember Anything Forever-ish was a link to Effective learning: Twenty rules of formulating knowledge and this post keeps what it promises. After learning how to properly formulate my facts, learning became easier. But I would advise against reading it when you're just starting with Spaced Repetition. In the beginning, forming a habit is much more important than proper technique but you should save this link and read it a few weeks later.

What I learned 💡

I'd like to share with you the areas I have learned new facts in to give you some ideas for your learning journey. Of course, each journey is different and ultimately everyone has to find their own path but those categories might help you discover some areas of interest.

Order of magnitudes ⚖️

Sometimes I read about a number and I cannot interpret it because I lack the context to understand it. What I try to do now is to learn some numbers of certain areas e.g. revenue:

After learning these numbers, whenever someone tells me the revenue of a new company, I can compare it and understand if this number is high or low. Some other magnitudes that I learned this way:

Current job 👨‍💻

I have worked as a programmer for five years and studied information systems before that. That's plenty of time to forget a lot of the basics I learned at university but Spaced repletion allowed me to recap:

New job areas 📊

For me, data visualization is an area where I want to dive further and I have been using Spaced Repetition to learn the basics:

Books 📚

Books are full of knowledge worth keeping and it's always sad when that knowledge fades away after some years. With Spaced Repetition you can stop this. I have summarized facts from:

General and recent knowledge 🤓

By starting with minor facts learning doesn't feel overwhelming anymore. This way

There are so many things that I always thought I should know, but starting to learn those felt overwhelming. By starting with minor facts learning doesn't feel overwhelming anymore. This way I learned:

Conclusion 🎇

I am looking forward to the next 100 days of Spaced Repetition and I am curious if I am going to use it differently than I am using it now. I hope this article got you some ideas about why you should use Spaced Repetition. If you're already using it maybe you found some inspiration about additional things to learn.

I would be happy to receive feedback or ideas about this topic. You can contact me by mail or Twitter.