The research in full
What spaced repetition is
Spaced repetition means coming back to what you learned several times, with gaps in between, instead of in one long session. Retrieval practice means pulling it out of memory, with a question or a quiz, instead of reading it again.
The two work best together: short recall questions, spread out over days and weeks. That combination is what the research below supports, and what Origin’s Munin schedules after every module.
Where the forgetting curve comes from
In 1885 Hermann Ebbinghaus published the first experiments on forgetting. He was his own only subject. He learned lists of nonsense syllables, relearned them after delays from 20 minutes to 31 days, and measured how much time the relearning saved. The saving fell fast at first and then more slowly: the forgetting curve.
In 2015, Murre and Dros repeated the experiment and got a very similar curve. The method matters, though: the curve describes relearning time for meaningless syllables, for one person. It does not tell you what share of a real course your learners will forget, and nobody can give you that number.
What the studies found
Spacing beats cramming. A 2006 review by Cepeda and colleagues pooled 839 assessments from 317 experiments: spreading study sessions out gave better long-term recall than massing them together. A follow-up with more than 1,350 people found that the best gap grows with how long you need to remember. For a test one week later, the best gap was about 20 to 40 percent of that week; for a test a year later, about 5 to 10 percent of the year.
Recall beats rereading, but not straight away. In a 2006 study by Roediger and Karpicke, students read a short text and then either read it again or tried to recall it:
| Final test | Read again | Recalled |
|---|---|---|
| After 5 minutes | 81% | 75% |
| After 2 days | 54% | 68% |
| After 1 week | 42% | 56% |
Rereading won on the spot. Recall won two days and one week later. In a 2008 study of Swahili–English word pairs, students who kept being tested remembered about 80 percent a week later; students who stopped being tested once they knew a word remembered 33 to 36 percent. The students predicted the same result for every method.
Two techniques rated high. In 2013, Dunlosky and colleagues reviewed ten common study techniques. Only two were rated high utility: practice testing and distributed practice. Rereading, highlighting and summarising were rated low.
Spaced recall beats massed recall. A 2021 meta-analysis of 29 studies by Latimier, Peyre and Ramus found a clear benefit for spacing out recall practice, even after correcting for publication bias. Gaps that keep growing did not beat equal gaps.
Where the evidence is thin
Most of these studies were done with school and university students, often with word lists, facts or short texts in a lab. That is a narrow slice of real teaching.
- For adults in training, a 1999 meta-analysis of 63 studies by Donovan and Radosevich also favoured spaced practice, with the size of the effect depending on the task.
- In real classrooms, a 2021 meta-analysis of 222 studies with 48,478 students found that regular quizzing improved learning.
- In health-professions education, a 2020 review found that “spaced learning” is often poorly defined, which makes studies hard to compare.
So the direction is consistent, but there is less evidence for adults at work than for students, and the exact gains in your own courses are unknown until you measure them.
Myths to leave out
- “We forget 70 percent within a day.” No study supports a universal figure. Ebbinghaus measured relearning time, not what share was forgotten.
- “Reviews must come at ever-longer intervals.” In the 2021 meta-analysis, growing gaps did not beat equal ones.
- “Testing always beats rereading.” On an immediate test, rereading won. The advantage of recall shows up days later.
- “Teach to each learner’s learning style.” A 2008 review by Pashler and colleagues found no adequate evidence for it, and in 2021 the Swedish Institute for Educational Research wrote that learning styles seem largely to lack scientific support.
How Munin puts it to work
Munin is the part of Origin that takes over after a module ends. For every skill in the module, it plans short reviews: a two-minute question set, sent just before the skill is likely to fade, and repeated until the skill graduates. A learner never has more than two reviews open at once, and can snooze one.
The timing comes from FSRS, an open-source scheduling algorithm that models each item’s difficulty, how stable the memory is, and how likely it is to be recalled today. The flashcard app Anki has offered FSRS as a scheduler since version 23.10. FSRS is tested on how well it predicts recall; its effect on course outcomes is not measured in the studies above.
We do not publish retention figures for Origin yet. When we do, they will come from our own learners, with the method stated on this page.
Using it without any platform
None of this needs software. Teachers can use it tomorrow:
- Start a lesson with three questions on last week’s material, answered from memory.
- Replace a reread with a short quiz, even an ungraded one.
- Return to a topic after a few days, then after a few weeks, instead of covering it once.
- Give feedback on the answers, so wrong recalls get corrected.
- Tell learners why: most feel that rereading works better, even when it does not.
Sources
Every study named on this page, with a link to the original. Checked 30 September 2026.
- Ebbinghaus, H. (1885). Über das Gedächtnis. Leipzig: Duncker & Humblot. English translation 1913: psychclassics.yorku.ca/Ebbinghaus/index.htm
- Murre, J. M. J., & Dros, J. (2015). Replication and analysis of Ebbinghaus’ forgetting curve. PLOS ONE, 10(7), e0120644. doi.org/10.1371/journal.pone.0120644
- 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), 354–380. doi.org/10.1037/0033-2909.132.3.354
- 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), 1095–1102. doi.org/10.1111/j.1467-9280.2008.02209.x
- Roediger, H. L., & Karpicke, J. D. (2006). Test-enhanced learning: Taking memory tests improves long-term retention. Psychological Science, 17(3), 249–255. doi.org/10.1111/j.1467-9280.2006.01693.x
- Karpicke, J. D., & Roediger, H. L. (2008). The critical importance of retrieval for learning. Science, 319(5865), 966–968. doi.org/10.1126/science.1152408
- 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), 4–58. doi.org/10.1177/1529100612453266
- Kang, S. H. K. (2016). Spaced repetition promotes efficient and effective learning. Policy Insights from the Behavioral and Brain Sciences, 3(1), 12–19. doi.org/10.1177/2372732215624708
- Latimier, A., Peyre, H., & Ramus, F. (2021). A meta-analytic review of the benefit of spacing out retrieval practice episodes on retention. Educational Psychology Review, 33(3), 959–987. doi.org/10.1007/s10648-020-09572-8
- Donovan, J. J., & Radosevich, D. J. (1999). A meta-analytic review of the distribution of practice effect. Journal of Applied Psychology, 84(5), 795–805. doi.org/10.1037/0021-9010.84.5.795
- Yang, C., Luo, L., Vadillo, M. A., Yu, R., & Shanks, D. R. (2021). Testing (quizzing) boosts classroom learning: A systematic and meta-analytic review. Psychological Bulletin, 147(4), 399–435. doi.org/10.1037/bul0000309
- Versteeg, M., et al. (2020). Conceptualising spaced learning in health professions education: A scoping review. Medical Education, 54(3), 205–216. doi.org/10.1111/medu.14025
- Pashler, H., McDaniel, M., Rohrer, D., & Bjork, R. (2008). Learning styles: Concepts and evidence. Psychological Science in the Public Interest, 9(3), 105–119. doi.org/10.1111/j.1539-6053.2009.01038.x
- Skolforskningsinstitutet (2021). Vad kan skolan lära av hjärnforskning? Skolforskningsinstitutet fördjupar 2021:01. www.skolfi.se/wp-content/uploads/2021/12/Skolforskningsinstitutet-fördjupar_hjärnforskning.pdf
- Skolverket, Lärportalen. Elevers kognitiva förmågor och studiestrategier i lärandet på gymnasiet (Partanen, 2021). larportalen.skolverket.se/api/resource/P05121588
- Open Spaced Repetition: the FSRS algorithm. github.com/open-spaced-repetition
- Anki manual: FSRS. docs.ankiweb.net/deck-options.html#fsrs