Just as “turnt,” “on fleek,” and “adulting” have become trending words in pop culture, so too has “spaced repetition” become a buzzword in education. Some educators are obsessed with it. Others say it’s just a minor hack for memorizing vocabulary.
So what’s “the tea?” In fact, spaced repetition is the key to all learning of knowledge-heavy subjects, from preschool literacy and numeracy exercises through high school, corporate training, and beyond. And yet it remains the most underrated and underutilized learning principle in the history of education.
In this article, I’ll explain exactly why spaced repetition is the secret to overcoming learning loss, and why all educators should incorporate it into their teaching methods.
Let’s start with a story.
Once upon a time in Panama
In 2006, I lived and worked in Panama and so it became a priority to learn Spanish. On weekends, I’d visit a friend on his farm in the Panamanian countryside, and this scarecrow would always catch my attention. And yet, try as I might, I could never seem to remember the Spanish word for it.
It’s espantapájaros. (Here’s how you pronounce it.) Go on, say it out loud yourself!
It’s a hard word, right?
Well, now multiply that by the thousands of new hard words and verb conjugations that I needed to internalize if I was to hold professional conversations with my Panamanian colleagues.
None of the usual language apps, which progressed linearly through vocabulary, worked. So, as a shameless devotee of Excel, I captured new words in a spreadsheet, numbered them on a scale of 1-5 based on how well I knew them, and then “sorted” the list from 1’s through to 5’s. This allowed me to repeatedly test myself on the words and phrases I struggled with (rated 1’s and 2’s), while only occasionally reviewing those I felt comfortable with (4’s and 5’s).
Within weeks of practicing my Spanish this way, I felt an order of magnitude more conversant.
Flattening the “Forgetting Curve”
This experience led to such a keen fascination in the science of learning that I returned to the United States to embark upon a Masters in Education Technology at Columbia University. There, I discovered that the technique I had so successfully used to drill myself on Spanish had a name—spaced repetition—and cognitive scientists had been talking about it ever since Hermann Ebbinghaus first illustrated the “forgetting curve” 140 years ago.
What this curve illustrates is the exponential drop-off of memory retention in the days after initial exposure. In other words: if a piece of information isn’t repeated to you again, you’re half as likely to remember it by tomorrow, and 90 percent likely to have totally forgotten it in a week. That’s just how the brain works: use it or lose it.
But if you add your first repetition very soon, within 24 hours of initial exposure to that information, you’ll strengthen that memory trace just when it’s on the cusp of plummeting over the edge of your memory. And this allows you to go LONGER between each subsequent repetition, basically shifting out and flattening that forgetting curve.
Add a second, third, and fourth repetition, and that information becomes increasingly ingrained in our working memory.
This is spaced repetition in motion! And it’s so intuitive and powerful that cognitive scientists have been flooding academia with thousands of studies for decades, showing how effective it is as a learning tactic. So, then why isn’t it a core tenet of the modern education system? And why do almost all curricula progress linearly through their subjects without any systematized attempt to help students continuously review older concepts until they’re permanently banked in their brain?
A world without spaced repetition
As proof of how bad that education is without spaced repetition, let me ask you a question:
How do you say “scarecrow” in Spanish again?
You forgot, didn’t you?
I literally just “taught” you this word less than two minutes ago, yet I’d bet good money that most of you reading this have already completely forgotten it.
It’s not your fault. Forgetting is simply how the human brain works. If I really wanted you to learn how to say “scarecrow” in Spanish, I should have asked you to repeat espantapájaros again 30 seconds after the first time (while that hard concept was still fresh in your memory) and then again after two minutes, 10 minutes, etc. with each interval getting longer and longer.
The same thing goes for other K-12 subjects and skills far beyond foreign language vocabulary. The list of applications is nearly infinite; spanning nearly all types of academics, professional certifications, and personal development pursuits. In terms of efficiency, spaced repetition eats every other tactic for breakfast.
An effective spaced repetition system
If your goal is to really retain new learning—or help students retain new learning—then what you need is a systematic way to organize the knowledge into a format that allows you to adaptively repeat it at the optimal intervals for your unique pace of learning. Then, spend more time drilling yourself on the harder concepts (espantapájaros) and less time on the easier concepts (hola).
A great vehicle for this exercise are flashcards, which not only allow you to break a subject down into its atomic facts, but also to sort those concepts into “difficult” vs “easy” piles and repeat accordingly. (Digital flashcard apps take things even further with their in-built spaced repetition algorithms.)
In conclusion, spaced repetition can guarantee that your knowledge is constantly building rather than having your brain be a “leaky bucket”. And while it remains an underrated and underutilized learning principle, there are tools at our disposal that can readily help any student of any subject leverage this powerful tactic to learn much more efficiently.
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