Spaced Repetition: How To Remember Everything You Learn

The amount of time we spend revising is always a controversial issue - some people prefer to downplay how much time they’ve spent revising whereas others are keen to tell you how much revision they’ve done. The fact is we’re all different in how much time we spend studying but if active recall is an effective technique, the next question I want to address is how we should be using it to enhance our performance. This is where spaced repetition comes in.

Spaced Repetition vs Cramming – The Theory and Evidence

As the name suggests, spaced repetition involves spacing your revision and reviewing topics, ideally by active recall, at specific intervals over a period of time.

It can be explained by the ‘forgetting curve’ – an idea that has been around in the psychology literature for over one hundred years. The forgetting curve is the idea that over time we forget things at an exponential rate – akin to the half-life of radioactive substances if you want a scientific analogy!

The way we can take advantage of the forgetting curve is through breaking the cycle by reviewing material at spaced intervals. This might be obvious to you but its importance cannot be overstated. The more that we practice and the more spaced this repetition becomes, the more likely we are to encode this information into our long-term memory.

In essence, the idea behind spaced repetition is that you allow your brain to forget some of the information to ensure that the active recall process is mentally taxing. The psychology literature suggests that the harder that your brain has to work to retrieve information, the more likely that that information will be encoded.

By spacing our repetition by a day, 3 days, then a week, we allow ourselves to forget some of the information such that when we revise the topic – through active recall – it takes active brain power. Rereading, on the other hand, has low utility because it is a passive exercise - just testing yourself once has been shown to be more effective than rereading the same passage four times.

What’s even more astounding is that evidence suggests that, even within the same study session, spaced repetition can be a more efficient technique in terms of retaining information. A 2011 study involving four groups of students who were tasked with trying to learn words in Swahili found that recalling information even within the same session had dramatic benefits. In the study, one group only studied the words once and this didn’t produce impressive results. The second group saw each word once and then had to recall a word once before being tested and, as you can see from the graph, just through recalling a word once, your performance increases. The third group had to recall the same words multiple times which produced similar results to Group 2.

However, most interestingly, the final group saw each word, recalled it, then had a gap of a few more words before recalling the first word again. In effect, this final group spaced their recall and, as the graph illustrates, the results are astonishing.

The students were doing exactly the same work – the only difference being that their recall was spaced out compared to groups 2 and 3. This study not only emphasises the power of active recall but also provides firm evidence of the power of spaced repetition and how we only need to restructure our revision slightly to obtain a substantial improvement in our ability to remember and recall information.

This active recall-spaced repetition combination can easily be adapted into our studying. For instance, let’s say you studied Topic 1 and Topic 2 one morning and planned to move to Topic 3 and Topic 4 in the afternoon. The results from this study demonstrate that you should go back to Topic 1 and write down – through active recall – what you can remember before moving onto Topic 3. You would then repeat this for Topic 2 after having studied Topic 3 and so forth.

In essence, spaced repetition over days and weeks as well as reviewing content on the same day, can both be extremely helpful for improving exam performance.

Applying Spaced Repetition

In practical terms, applying active recall and spaced repetition could be as simple as taking a pen and paper at the end of the day and answering your active recall questions, or constructing a spider diagram of what you’ve learnt – all with your book closed obviously!

But I know that different techniques work better for some people compared to others. The following strategies are the ones that worked effectively for me - if you’re struggling with your studying, then perhaps give these a try.

My 'Magic' Spaced Repetition Spreadsheet System

As you may have seen in past videos, one of the key techniques that I’ve found particularly effective is a spreadsheet system that I adapted using Google Sheets. (NB: I preferred using Google Sheets specifically as it gives you access across devices and allows you to update your spreadsheet wherever you are – removing unnecessary friction of having to rely on having the latest Excel software to open certain files!).

The approach involves making a sheet for each subject and then in the first column of each spreadsheet, you list all the topics for that subject. To do this, it is essential to ‘scope’ your subject. This might sound simple and obvious but in offering advice to students over recent years, it’s been quite astounding how few students know their course inside out or know exactly what topics they have in their subject. So, even if it takes a whole day to compile using your syllabus and/or past exam papers, scoping your subject is essential in order to produce a list of all the topics that you need which will make revision far more straightforward.

Once you’ve done this, the actual spreadsheet system is very simple but, as I’ve found, extremely effective. In essence, every time you study a topic and, critically, actively recall information from that topic, then you write the current date in the column along in the spreadsheet. Marking a date is not just when you have read a chapter in the textbook – that is too passive - you can only mark a date when you have actively recalled information, facts, quotes or essay plans. After having studied other topics and repeated this exercise, you build up a list of repetitions as well as a table which enables you to keep track not only of when you last studied that topic but, by colour coding each topic based on your comprehension, you can also start to rank how confident you are on each particular topic.

Below is an example of a spreadsheet that I used in my Third Year when I was doing psychology. Once I had actively recalled the essay plan by drawing a spider diagram for each one, I would write the date in the corresponding box in the spreadsheet. I then colour coded each box based on how accurate my recall was which gave me a very visual representation of the areas in which I was stronger and/or weaker.

Summary / Extra Notes

Active recall and spaced repetition provide a brilliant blend that can improve the efficiency and efficacy of your studies.
Spaced repetition is better than cramming – even within a single study session.
The spreadsheet system is very simple, gives a pictorial representation of where you are for each of your subjects and allows you to more effectively plot your daily timetables.

And if you found this helpful...

I think you'd also like my Studying page. It breaks down a few more methods including Active Recall - which I'd highly recommend checking out.