The Ultimate Guide to Spaced Repetition
You've heard the buzzword. Maybe you've tried Anki and quit. Or maybe you're just tired of forgetting everything you study. This guide is a deep dive into the science, math, and practical application of the world's most effective learning technique.
Chapter 1: Foundations
It all started with Hermann Ebbinghaus (1850-1909). He memorized nonsense syllables (DAX, BOK, YAT) and tested himself. He found that memory decay is exponential.
Spaced Repetition is the act of interrupting this curve. Each interruption resets the curve, but flatter than before.
Chapter 2: The Algorithm
Modern apps use algorithms to predict the optimal time to review.
SM-2 (SuperMemo 2)
Used by Anki and SpaceRep (modified). It uses a user's grade (Again, Hard, Good, Easy) to calculate an Ease Factor.New Interval = Old Interval * Ease Factor
FSRS (Free Spaced Repetition Scheduler)
A newer, machine-learning based algorithm. It's more complex but claims higher accuracy.
Chapter 3: Creating Effective Cards
The Minimum Information Principle: Simple is easy. Complex is hard. Break complex topics into multiple atomic cards.
- Use Images
- Use Cloze Deletion (Fill in the blank)
- Provide Context
Chapter 4: Scheduling Strategy
The biggest friction point is the schedule. If you miss a day, reviews pile up. Traditional apps punish you for missing a day.SpaceRep works differently by integrating with your calendar to re-distribute the load.
Chapter 5: Tools
Analog (Leitner System): Physical boxes. Good for tactile learners. Hard to manage 1000+ cards.
Digital Apps: Anki, Quizlet, SpaceRep. Essential for long-term tracking.
Chapter 6: Mistakes to Avoid
- The "Yes/No" Trap: Don't just flip the card and say "Yeah, I knew that." FORCE yourself to say the answer out loud.
- Over-tagging: Don't spend more time organizing cards than studying them.