Spaced Repetition
Cramming the night before loads information into short-term memory that has mostly evaporated by the exam. Spaced repetition does the opposite — it builds memories that last.
The forgetting curve
In the 1880s, psychologist Hermann Ebbinghaus measured how quickly we forget. Without review, we lose the majority of newly learned material within days. But each well-timed review resets the curve and flattens it, so memory decays more slowly each time.
The spacing effect
Reviewing material at increasing intervals produces stronger memories than the same number of reviews packed together. This is one of the most robust findings in all of learning science. The optimal interval expands as the memory strengthens.
A practical schedule
A simple, effective schedule for a new concept:
- Review 1: same day you learn it.
- Review 2: next day.
- Review 3: after 3 days.
- Review 4: after 1 week.
- Review 5: after 2–3 weeks.
- Then monthly until the exam.
Tools that automate the schedule
Spaced-repetition software (SRS) such as Anki schedules each flashcard for you, showing cards just before you would forget them. Combine SRS with active recall for maximum effect — the flashcard format forces retrieval and the algorithm handles the spacing.
Frequently Asked Questions
- How long should each spaced session be?
- Short — 15 to 30 minutes is plenty. The benefit comes from the spacing, not from marathon sessions.
- Can I use spaced repetition for an exam next week?
- Yes, on a compressed schedule: review today, tomorrow, in two days, and the day before. It still beats one long cram.
- What's the difference between spaced repetition and active recall?
- Active recall is the act of retrieving; spaced repetition is the timing of those retrievals. They work best together.