What is spaced repetition?
5 min read · updated 2026-09-02
Cramming works for about forty-eight hours, then the knowledge evaporates. Spaced repetition is the counter-strategy: revisit each topic several times, with gaps that grow each time, so memory is strengthened exactly as it starts to fade.
The forgetting curve
Hermann Ebbinghaus mapped it in the 1880s and replications have held up for over a century: after learning something new, most of the forgetting happens fast, within days. But each successful review flattens the curve. A topic reviewed after a day, then three days, then a week, then a fortnight becomes dramatically more durable than a topic reviewed four times in one evening.
The effort is the point. A review that feels slightly hard (you half-remember, then it comes back) is doing more good than a review that feels easy, which usually means it was done too soon.
How to schedule it
Families do not need software to space revision, just a calendar and a simple cycle:
- ✓ Lesson or first learn: day 0. Same evening, a 10-minute review of notes
- ✓ Day 2-3: attempt recall questions on the topic (see retrieval practice)
- ✓ End of week: one exam question on the topic, marked
- ✓ Three to four weeks later: the topic reappears in a mixed quiz alongside older topics
- ✓ Any topic that fails the recall test jumps back to the front of the queue
Why cramming loses
The night-before marathon can carry a student through a single test the next morning. It cannot build the connected, durable knowledge that later topics depend on, which is why crammers who scrape a topic test often collapse in the cumulative exam. Maths is the clearest case: this month's calculus is next month's exam question and next year's mechanics.
FAQs
How is spaced repetition different from just revising more?＋
It is about timing, not volume. The same total hours spent on four spaced reviews of a topic produce far better retention than four back-to-back hours, because each review lands while the memory is partly faded and must be rebuilt.
Do flashcard apps handle the spacing for you?＋
Apps can schedule cards automatically, which helps for facts and definitions. But subjects like maths and essay writing need spaced exam questions and spaced essay plans, which a calendar planner handles better than any app.
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