- Ebbinghaus's forgetting curve explained
- How spaced repetition flattens that curve
- A simple 5-session review schedule
- Why spaced repetition beats cramming
- How to apply it with DoQuizzes
The Forgetting Curve
In 1885, German psychologist Hermann Ebbinghaus studied his own memory and charted the forgetting curve - the rate at which newly learned information decays without reinforcement. His findings were stark:
| Time after learning | Memory retained (no review) |
|---|---|
| 20 minutes | 58% |
| 1 hour | 44% |
| 1 day | 33% |
| 1 week | 25% |
| 1 month | 21% |
Without review, you forget roughly two-thirds of new information within a day. The critical insight Ebbinghaus also discovered: each review resets and flattens the curve. After reviewing something once, you forget it more slowly. After a second review, more slowly still. The curve becomes increasingly flat with each spaced repetition.
How Spaced Repetition Works
The core mechanism: review material just before you would naturally forget it. Reviewing too soon wastes time. Reviewing too late means re-learning from scratch. Reviewing at the right interval - the edge of forgetting - strengthens the memory maximally with minimum time investment.
Modern spaced repetition systems like Anki calculate this interval algorithmically. You rate how well you recalled each card, and the algorithm schedules the next review accordingly. Easy cards get reviewed less frequently; hard cards get reviewed more often.
A Simple Spaced Repetition Schedule
You do not need a dedicated app to benefit from spaced repetition. Here is a straightforward schedule to apply with your DoQuizzes flashcard sets:
| Session | When | What to do |
|---|---|---|
| 1st | Day 1 | Study the new set - two full passes with active recall |
| 2nd | Day 2 | Quick review - focus on cards you missed yesterday |
| 3rd | Day 4 | Full review of the entire set |
| 4th | Day 11 | Quick review - one full pass |
| 5th | Day 25 | Final check before exam or long-term consolidation |
Following this schedule with a 10-card set takes roughly 5 minutes on Day 1, 2 minutes on Day 2, and under 2 minutes per session after that. In exchange, you retain the material for months rather than days.
Spaced Repetition vs. Cramming
Cramming - studying large amounts in a single session just before a test - produces measurable short-term recall but almost no long-term retention. Studies consistently show that students who cram forget more than 80% of the material within one month.
Spaced repetition produces the opposite pattern: slightly lower recall on the test day, but significantly higher retention a month later. If your goal is to actually learn - for a cumulative course, a certification, or a language - spaced repetition is the only approach that scales.
| Method | Test day recall | 1-month recall |
|---|---|---|
| Cramming | High (~70%) | Low (~20%) |
| Spaced repetition | Moderate (~65%) | High (~70%) |
Why Flashcards Are the Best Format for Spaced Repetition
Spaced repetition requires isolating individual pieces of information so they can be reviewed independently. A card - one concept on the front, one answer on the back - is the perfect atomic unit for this. You cannot apply spaced repetition to a paragraph of text; you can apply it to 15 cards that cover the same paragraph's key concepts.
AI generation makes this practical at scale: instead of manually breaking notes into card-sized chunks (a 30-45 minute task), you paste your notes and get 10-30 perfectly formatted cards in seconds, ready to slot into any spaced repetition schedule.