Spaced repetition
Spaced repetition is a study method in which you review information at increasing intervals. Each successful review makes the memory more durable, so the next one can wait longer.
Why does it work?
Memory fades along a forgetting curve. Each successful recall makes the next decline slower, so reviews can be spaced further apart.
The forgetting curveWhich algorithm decides when?
Most apps use SM-2, from 1987, or the newer FSRS, which estimates how likely you are to recall each card and schedules it when that likelihood falls to a target.
Compare the algorithmsWhich app should you use?
Anki is the free reference for power users. Simpler apps trade some control for less setup.
Spaced repetition appsContents
Learn
The science of memory and study
- Active recall
- The forgetting curve
- The spacing effect
- Spaced repetition schedule
- Does spaced repetition work?
How spaced repetition works
Memory fades along a forgetting curve, first measured by Hermann Ebbinghaus in 1885. Each successful review makes that curve flatter, so the next review can wait longer than the one before: a day, then a few days, then weeks and months.
Spaced study beats cramming for long-term retention, a finding known as the spacing effect. A flashcard app tracks every card and schedules its next review with an algorithm such as SM-2 or FSRS. The method suits anything you must recall on demand: vocabulary, medicine, law, definitions.
Apps
Each app profile covers the same questions: price, platforms, scheduling and the cards you can make, checked against official sources.