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How Spaced Repetition Works


The Problem with Cramming

Research shows that cramming (studying everything at once) leads to poor long-term retention. You might pass tomorrow's test, but you'll forget most of it within a week.


The Solution: Spaced Repetition

Spaced repetition shows you cards at increasing intervals based on how well you know them. Cards you struggle with appear more often; cards you know well appear less frequently.


FSRS: The Algorithm Behind FluentFlash

FluentFlash uses FSRS (Free Spaced Repetition Scheduler) — the most advanced spaced repetition algorithm available. It was developed through open-source research and outperforms older algorithms like SM-2 (used by traditional Anki) by 20-30%.


How FSRS Works

After each review, FSRS calculates:

  • Stability: How well the memory is stored (higher = longer intervals)
  • Difficulty: How hard this card is for you (adjusts per card)
  • Due date: When you should see this card next for optimal retention

  • What Your Ratings Mean

  • Again: "I didn't know this" → Short interval, stability decreases
  • Hard: "I struggled but eventually remembered" → Shorter-than-normal interval
  • Good: "I knew it after thinking" → Normal interval based on stability
  • Easy: "I knew it instantly" → Longer interval, stability increases more

  • Target Retention

    FluentFlash targets 90% retention — meaning you should correctly remember 9 out of 10 cards when they come up for review. This is the optimal balance between review efficiency and long-term memory.


    Why FSRS is Better Than SM-2

  • 20-30% fewer reviews for the same retention level
  • Adapts to each individual card's difficulty
  • Handles missed reviews gracefully (no "Anki bankruptcy")
  • Personalizes scheduling after 400+ reviews
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