The Science of Spaced Repetition

Have you ever crammed for an exam, only to forget everything a week later? You're not alone. Research shows that traditional study methods waste up to 80% of your time reviewing material you already know.

What is Spaced Repetition?

Spaced repetition is a learning technique that spaces out review sessions at increasing intervals. Instead of reviewing everything every day, you review each piece of information just before you're about to forget it.

The Evolution: From SM-2 to FSRS

For decades, most flashcard apps used the SM-2 algorithm, created by Piotr Wozniak in 1987. While revolutionary for its time, SM-2 treats all learners the same.

FSRS (Free Spaced Repetition Scheduler) is the next generation. Developed by the open-source community and now adopted by Anki itself, FSRS:

• Adapts to your memory — learns your personal forgetting curves
• More accurate scheduling — reduces unnecessary reviews by up to 30%
• Backed by research — based on modern memory models

How iwill.study Uses FSRS

When you review a card on iwill.study, you rate your recall:

• Again — you forgot it completely
• Hard — you struggled but got it
• Good — you remembered with some effort
• Easy — it was effortless

FSRS uses these ratings along with your history to calculate the optimal time to show you that card again. The result? You learn more in less time.

Getting Started

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