Spaced repetition: study less, remember longer

You learn a chapter inside out, and a week later almost nothing is left. That's not a motivation problem or a “faulty” memory: it's how the brain normally works, measured as far back as 1885 by Hermann Ebbinghaus and his famous forgetting curve. The good news: that curve can be hacked.

The forgetting curve in one sentence

Without review, forgetting is brutal at first, then slows down: you lose most of it within the first few days. But every time you force yourself to recall a piece of information just before it disappears, the curve restarts from higher up and falls more slowly. Repeat that a few times and the information holds for months.

The principle: review right before you forget

Spaced repetition means spacing out your reviews of the same information more and more: first the next day, then a few days, then weeks. Two ingredients make it formidable: spacing (reviewing when it's slightly hard forces the brain to consolidate) and active recall (asking yourself the question and retrieving the answer from memory, instead of rereading).

The intervals that work in practice

1. 1Day 0: you learn the concept (course, study notes).
2. 2Day 1: first recall from memory. This is the pass that saves the most retention.
3. 3Day 3: second recall. Quick if you did the first one.
4. 4Day 7, then day 14: the concept becomes stable.
5. 5Day 30 and beyond: an occasional recall is enough to maintain it.

These intervals are a guideline: the real rule is adaptive. A failed card comes back quickly; a card you got right easily gets spaced out further. That's exactly what SM-2-style algorithms do (the one behind Anki and ASSIMIA): they compute, card by card, the optimal moment for the next recall.

How to get started without overcomplicating it

• Turn each set of study notes into questions (flashcards) as the semester goes, not the night before finals.
• 10 to 15 minutes a day is enough: consistency beats volume.
• Trust the algorithm: don't re-review what it isn't showing you — that's precisely the point.
• Start early: spaced repetition is unbeatable over a semester, useless in 48 hours.