Spaced repetition is the foundation of efficient vocabulary learning. But what makes it so powerful, and how can you use it to remember words forever?

The Forgetting Curve

In 1885, German psychologist Hermann Ebbinghaus discovered the forgetting curve — a mathematical formula that describes how information is lost over time when there’s no attempt to retain it.

Key findings:

  • Within 1 hour: You forget ~50% of new information
  • Within 24 hours: You forget ~70%
  • Within 1 week: You forget ~90%

The good news? Each review resets the forgetting curve, and the interval before the next forgetting becomes longer. This is the core principle of spaced repetition.

How Spaced Repetition Systems Work

A spaced repetition system (SRS) tracks each word you’re learning and schedules reviews at optimal intervals:

  1. First review: After 1 day
  2. Second review: After 3 days
  3. Third review: After 7 days
  4. Fourth review: After 14 days
  5. Fifth review: After 30 days
  6. Subsequent reviews: Intervals continue to grow

If you forget a word, the system resets its interval, showing it more frequently until you’ve mastered it.

Why SRS Beats Traditional Methods

Studies consistently show that spaced repetition outperforms other learning methods:

  • Cramming: Quick short-term gains, but 90% forgotten within a week
  • Massed practice: Repeating words in one session — inefficient and boring
  • Spaced repetition: 200-300% better long-term retention with less total study time

Best Practices for SRS Learning

  1. Review every day: Consistency is more important than volume. 15 minutes daily beats 2 hours weekly.
  2. Be honest with yourself: If you don’t know a word, mark it as “forgotten.” The system needs accurate feedback.
  3. Learn in small batches: Add 10-20 new words per day, not 100 at once.
  4. Use multiple exercise types: Flashcards, typing, and listening exercises reinforce different memory pathways.
  5. Don’t skip reviews: Missing days causes a backlog that’s hard to catch up on.

PairLingua’s SRS Engine

PairLingua uses a modified SM-2 algorithm (the same family as Anki) with adaptive scheduling based on your performance. The system automatically:

  • Calculates optimal review intervals for each word
  • Adjusts difficulty based on your accuracy
  • Prioritizes words you’re struggling with
  • Tracks your daily streak and retention rate

Start studying with spaced repetition — it’s free.