The Holy Grail: Spaced Repetition

3 min readMar 14, 2022


According to a study undertaken by academics at the University of California-San Diego, humans are bombarded with the equivalent of 34 gigabytes of data every day. Today, it is more important than ever to learn to retain information as we are constantly bombarded with new information. So how do we retain all this information?

Read more: Drowning in content and how to tackle it.

We’ve all been told right from our childhood that to remember things, we need to practice. And it actually worked! The theory behind this practice is called Spaced Repetition.

As the name suggests, spaced repetition is where you space your repetition/revision of particular subjects over a period of time. It is in contrast to cramming; when you cram for a test the next day, you can probably remember quite a lot of it because it’s in your short-term memory, but by the next day or the following day, you’ve completely forgotten all of it. So cramming is not ideal if we’re talking about retaining stuff in the long-term memory. The idea behind spaced repetition is that instead of cramming things into a single day, we spread out our revision over time. We ideally review topics by active recall at particular intervals. The reason why it works is because of something called the forgetting curve.

What is the forgetting curve?

Hermann Ebbinghaus laid the groundwork for spaced repetition research when he proposed that information loss follows a forgetting curve over time but that forgetting may be reset with repetition based on active recall.

The forgetting curve simply shows how information is lost over time when there is no attempt to retain it.

From 1880 to 1885, Hermann Ebbinghaus ran a study and published his hypothesis in 1885 as Memory: A Contribution to Experimental Psychology. He hypothesised that each learning repeat lengthens the optimum gap before the next repetition is required. Initial repeats may need to be done within days for near-perfect retention, but subsequent repetitions can be completed even after years.

Flatten the forgetting curve.

When information is built on previous knowledge, it is easier to remember, and the forgetting curve is flattened with each repeat. It appeared that by applying frequent training in learning, the information was solidified by repeated recalling.

With every revision, the exponential information loss curve gets flattened. The more revisions you do, the more likely you are to remember it for a longer period of time. And if you want to time your revisions, you can keep track of the last time you revised. This way, you’ll know how long it has been since your last revision and can revise it if you find it’s been a very long time. An important point to note is that no matter how many times you revise, the quality of your revisions also matter. Higher original learning is always better than doing revisions for the sake of it.

Flashcards are a great way to practice spaced repetition. Read more: What are Flashcards, and how to use them?

So, whatever revision method you pick to learn subjects, it should fundamentally slow down the forgetting curve. You could choose to do active recalling by writing down what you learnt, or you could simply read through the subject a couple of times or even try explaining it to other people. Start with any method of your wish and find whether it slows down the forgetting curve. If not, it’s time to move on to the other methods. Because no matter how much time you put in, if it doesn’t yield the results, you are looking for, it’s simply not worth it.

It turns out that revising does work after all. If you didn’t know why it worked, now you know the logic behind it!

-Varun, content writer




It’s not just about reading and writing. It’s about renewing your self-motivation.