Spaced repetition is the practice of reviewing information at increasing intervals over time — reviewing right before you’d naturally forget it. Instead of studying everything every day, you study each piece of information less and less often as you get better at recalling it.
The Spacing Effect
The spacing effect has been observed since the 1880s. Reviewing material spread over multiple sessions produces stronger memory than reviewing it for the same total time in one session. This is one of the most replicated findings in all of cognitive psychology.
How It Works in Practice
If you learn a fact today and review it tomorrow, then in 2 days, then in 4 days, then in 8 days — each review strengthens the memory trace more than the last. Eventually you can go weeks or months between reviews and still recall it accurately.
Leitner System as Spaced Repetition
The Leitner system is a physical implementation of spaced repetition. Each box corresponds to a review interval. Cards you know well move to boxes with longer intervals. Cards you don’t know return to Box 1 for daily review. The physical boxes make the abstract concept of spacing concrete and visible.
Spaced Repetition vs Cramming
Cramming produces short-term recall. Spaced repetition produces long-term retention. For exam prep the week before: cramming is acceptable. For skills you need months or years later: only spaced repetition works. Download the free 3-Box Schedule to start your own spaced repetition system today.
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The Leitner OS Dashboard is a Google Sheet with everything pre-built: a Due Today list, box-by-box counts, a rewrite queue for problem cards, and settings you can adjust in seconds. No app, no subscription, no installation.
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