Review just before you forget.
Spaced repetition: how to remember more by studying less
Spaced repetition is a study technique where you review material at increasing intervals over time, just before you are likely to forget it, instead of cramming it all at once. Each successful review lets the next gap grow longer.
The evidence
Why does spaced repetition work?
Memories fade quickly at first and then more slowly. Hermann Ebbinghaus documented this forgetting curve in 1885 by testing his own memory of nonsense syllables, and also found that spreading out repetitions made learning more efficient.
The spacing effect is one of the most reliable findings in learning research. A review by Cepeda and colleagues (2006) of hundreds of experiments found that spreading study sessions out leads to better long-term retention than massing them together.
How far apart should sessions be? Cepeda and colleagues (2008) found that the best gap depends on how long you need to remember: for a test in a week, review after a day or so; to remember for months, longer gaps of weeks work better.
Dunlosky and colleagues (2013) rated distributed practice, together with practice testing, as the two most useful study techniques in their review.
Step by step
How do you use spaced repetition?
- 1
Learn it once, properly
Make sure you understand the material and can answer the questions once before you start spacing it out.
- 2
First review: the next day
Test yourself again a day later. Expect to have forgotten some of it; that is normal.
- 3
Widen the gaps
If you remembered it, wait longer next time: a few days, then about a week, then a few weeks. If you forgot it, bring it back sooner.
- 4
Review what is due, every day
A short daily session on just the cards that are due beats a long weekly session on everything.
- 5
Add new material gradually
Add a manageable number of new cards each day, so your daily reviews do not pile up.
Watch out
What are the common mistakes?
Cramming everything the night before
Reviewing everything every day
Rating yourself too generously
Adding too much at once
Try it
How do you practise spaced repetition with student.study?
student.study's Review mode does the scheduling for you: cards come back when they are due, based on how well you remembered them last time.
Rate each card Again, Hard, Good or Easy. Cards you struggle with come back soon; cards you know well wait longer. Your dashboard shows how many cards are due today.
Every flashcard you study in a normal round also counts towards its review schedule.
FAQ
Spaced repetition: questions
How often should I review with spaced repetition?
A common pattern is the next day, then after a few days, then about a week, then a few weeks, widening the gap each time you remember and shortening it when you forget. Apps and the Leitner system handle the timing for you.
What is the difference between spaced repetition and active recall?
Active recall is how you study: by testing yourself. Spaced repetition is when you study: at increasing intervals. Combining them, by testing yourself on a spaced schedule, is one of the best-supported approaches in learning research.
What is SM-2?
SM-2 is a spaced-repetition scheduling algorithm created by Piotr Woźniak for SuperMemo in the late 1980s. It sets each card's next review date from how easily you remembered it, and many flashcard apps use a version of it.
Can I still use spaced repetition if my exam is next week?
Yes, with shorter gaps: study today, review tomorrow, again in two or three days, and once more the day before the exam. Starting earlier lets the gaps grow and the memories last longer.
Sources
Research referred to on this page
- Ebbinghaus, H. (1885). Über das Gedächtnis (Memory: A Contribution to Experimental Psychology). Duncker & Humblot, Leipzig.
- Cepeda, N. J., Pashler, H., Vul, E., Wixted, J. T. & Rohrer, D. (2006). Distributed practice in verbal recall tasks: a review and quantitative synthesis. Psychological Bulletin, 132(3). Read the paper (opens the publisher's page)
- Cepeda, N. J., Vul, E., Rohrer, D., Wixted, J. T. & Pashler, H. (2008). Spacing effects in learning: a temporal ridgeline of optimal retention. Psychological Science, 19(11). Read the paper (opens the publisher's page)
- Dunlosky, J., Rawson, K. A., Marsh, E. J., Nathan, M. J. & Willingham, D. T. (2013). Improving students' learning with effective learning techniques. Psychological Science in the Public Interest, 14(1). Read the paper (opens the publisher's page)
Last reviewed 9 November 2026
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