Spaced repetition: why it works and how to get started

You know the feeling: the night before a test, everything seems clear, and a week later only scraps of the same material are left. It’s not a sign of a bad memory - that’s how forgetting works for everyone. The good news: you can use it to your advantage.

Why we forget

In the late 19th century, Hermann Ebbinghaus tested on himself how quickly newly learned information fades. Most of it slipped away in the first hours and days, and after that the rate of forgetting slowed down. This shape is called the forgetting curve.

But the most important finding is a different one: every successful recall makes the next round of forgetting slower. Knowledge you review at the right moment stays with you longer.

The spacing effect

The same number of reviews gives longer-lasting results when you spread them over several days than when you squeeze them into a single evening. This is the spacing effect - one of the best-established findings in the psychology of learning. Cramming might get you through tomorrow, but it fades fast - and final exams, whether in college or at the end of high school, cover material from months ago.

A simple plan to get started

1. Day 0 - learn the material and right away give yourself a short quiz from memory.
2. Day 1 - first review.
3. Day 3 - second review.
4. Day 7 - third review.
5. Then every 2–3 weeks - until the exam.

The intervals don’t have to be exact to the day. What matters is that they keep getting longer, and that the things you struggle with come back more often than the ones you already remember well.

Recall instead of rereading

Reviewing isn’t the same as rereading your notes. Rereading creates the illusion that you know everything, because the text looks familiar. Active recall is much more effective: close your notebook and try to reproduce the definition, solve a problem or answer a question. Only then check.

The simplest tool for this is flashcards: a question on one side, the answer on the other. Cards you remember get set aside for longer, while the ones you struggle with come back sooner.