Spaced repetition (SRS) means reviewing each fact at increasingly long intervals. If you get it right, the next review moves further away; if you get it wrong, it comes sooner. You retain more in fewer hours: the meta-analysis by Cepeda et al. (2006) found better recall when study is spread over time than when it is massed.

Spaced repetition: study less and remember more

Spaced repetition (often called SRS, for spaced repetition system) is a study technique based on Ebbinghaus's forgetting curve. It maximizes retention by reviewing material at increasing intervals. If you are preparing for a demanding exam, the goal is not to put in more hours. It is to review each item at the right moment.

What SRS is and why it works

An SRS schedules reviews according to how likely you are to forget each item. Every time you recall an answer correctly, the system lengthens the interval before you see it again. If you get it wrong, the interval shortens. That mechanism uses the biology of memory to fix information with the least total study time.

Key concepts: the forgetting curve and Anki

  • The forgetting curve: Hermann Ebbinghaus showed that, without review, we forget around 70% of new information within the first 24 hours. The curve drops steeply at first and then levels off. Spaced repetition interrupts that drop just before the memory fades, resetting the curve and making it flatter each time, so the memory lasts longer.
  • Anki and the algorithm: Anki is the software that popularized digital spaced repetition. It automates what used to be done with shoeboxes of index cards (the Leitner system): it decides when you should see each card and shows you only what you are about to forget.

How to apply spaced repetition to exam preparation

Spaced repetition works on cards, summaries and active questions. A practical workflow:

  1. Break the syllabus into atoms: Do not try to memorize whole pages. Split each topic into small, indivisible facts: a deadline, a definition, an exception.
  2. Create active material: Turn those facts into question-and-answer cards or cloze deletions. Instead of reading "The Treaty of Rome was signed in 1957", write: "In what year was the Treaty of Rome signed? → [1957]".
  3. Learn it first: Understand the material before you put it into the system. Spaced repetition is for retaining, not for understanding.
  4. Review every day: Each day the system shows you the cards that are due. Clear your review queue daily, or the algorithm stops working in your favor.

For many students Anki is the default tool. Others prefer AI tools that create the cards and prioritize them automatically.

A practical example: one week of reviews

Imagine you study 30 new cards on Monday. With typical intervals of 1, 3, 7 and 21 days, you do short reviews on those days. If a card is hard, it goes back to a short interval and the system brings it back more often until it sticks. Over the long run this cuts review hours.

Common mistakes and how to avoid them

  • Overloaded cards: Cards with too much text or several questions on one side. Fix: follow the minimum information principle. One card, one fact.
  • Review backlog: Skipping several days leaves hundreds of cards pending, which is demoralizing. Fix: make reviews a daily habit, like brushing your teeth, even if it is only 15 minutes.
  • Memorizing without understanding: Trying to recall isolated facts without the context around them. Fix: make sure you understand why something is true before you make the card.
  • Grading yourself too generously: Marking a card "Easy" when you actually hesitated. Fix: be honest with the system. If you hesitated, you do not know it well yet.

Elaia: spaced repetition with the cards made for you

Elaia automates the creation of study material and organizes your reviews around what you get wrong. It generates flashcards from your own notes, prioritizes weak topics and adapts the intervals. Elaia asks more often about what you miss: it detects error patterns and gives you more practice on those items until they are consolidated.

Time efficiency: study less, perform better

The main practical advantage of spaced repetition is time. Instead of reviewing everything equally, you spend minutes on what you miss and stretch the intervals on what you already know. The result is fewer hours in front of the material with the same or better retention. By removing empty reviews (rereading what you already know), you free up time to cover new topics or to rest.

How to measure progress

Track your retention rate (the percentage of correct answers after a given number of days) and the time spent per item. A good spaced repetition routine reduces the total time needed to keep retention high.

Final recommendations

  1. Start as early as you can: Spaced repetition compounds over time. The earlier you start, the less you will have to study in the weeks before the exam.
  2. Mix subjects: Do not study a single block. Spaced repetition lets you mix cards from different topics, which is closer to the real exam and improves mental agility. See our guide to interleaving.
  3. Quality over quantity: 100 well-made, well-reviewed cards beat 1,000 badly designed cards that you abandon after a week.

In short: spaced repetition turns wasted hours into effective, measurable reviews. Adopt it, review at the right frequency, and let software handle the scheduling so you can put your energy into learning what matters.