Spaced repetition, explained simply

What is spaced repetition?

Spaced repetition is a revision method where you review the same material at increasing intervals: the next day, three days later, a week later, then a month later. At each review you answer from memory before checking. The point is to schedule each review for the moment the memory starts to fade, rather than rereading something you still know perfectly well.

Two ingredients do the work. Spacing forces your brain to rebuild the information instead of merely recognising it on the page. Active recall means you produce the answer before you see it. Rereading on a schedule is still rereading; the effort of retrieving is what fixes the material.

Why does the forgetting curve make last-minute cramming fragile?

The forgetting curve described by Ebbinghaus shows that freshly learned material drops away quickly in the first days, then decays more slowly. Cramming rides the top of that curve: you peak just before the exam and lose most of it afterwards. Spaced repetition does the opposite, because every successful recall flattens the curve and slows the next round of forgetting.

This is why a student can ace a November test and remember almost nothing by the time A-levels arrive. The material was never consolidated, only kept afloat for a few hours. For any terminal exam, cramming means paying for the same chapter twice.

Which intervals should you use?

A simple schedule is enough: review the next day, then after three days, then a week, then two weeks, then a month. Every time you retrieve the answer without hesitating, the card moves to the next interval. Every time you blank, it drops back by one step only, never to the beginning. That partial demotion rule is what keeps the workload realistic in a normal school week.

The dates are not sacred. Pushing a review two days later changes nothing; skipping three cycles in a row does. Aim for a session most days rather than a perfect calendar.

• Day 1 — the day after the lesson, while the context is still there.
• Day 3 — the first honest memory test, with the notes closed.
• Day 7 — the material starts to settle.
• Day 15 and day 30 — upkeep, a few minutes each.
• The day before the exam — only the cards you missed on recent passes.

How do you do spaced repetition without software?

The Leitner system takes ten minutes to set up with index cards and five envelopes. Each envelope has its own frequency: daily, every three days, weekly, fortnightly, monthly. A card you get right moves up one envelope; a card you miss drops down one. That is the whole system, and it runs on a desk with no account and no app.

Paper has one underrated advantage: backlog is visible. If the daily envelope is bulging, you are adding more cards than your revision time can absorb. Software often hides that behind a counter you learn to ignore.

• One question and one answer per card, front and back.
• Write the question as a real test, not as a chapter heading.
• Note the first review date on the back so you can track it.
• Twenty minutes a day beats three hours on Sunday.

What mistakes make people quit spaced repetition?

Three mistakes come up again and again: making too many cards at once, writing cards that are too long, and resetting everything after a week off. The first two inflate the daily session until it becomes impossible to sustain. The third destroys the main benefit of the method, which is precisely that you never start from scratch.

A card should hold an answer you can say out loud in a few seconds. If you have to recite a paragraph, split it. And after a break, reset nothing: clear the backlog over several days, prioritising the cards from the lowest boxes.

• Too many cards — cap yourself at ten or fifteen new cards a day at the start.
• Cards that are too long — one definition, one formula, one date, one cause — not a lecture.
• Ambiguous cards — if the answer depends on context, put the context in the question.
• Resetting after a break — catch up in small batches instead of starting over.
• Reviewing without testing — covering the answer is part of the method.

When should you switch to software, and which kind?

Paper runs out of road at around a hundred cards, or as soon as you revise several subjects in parallel, because sorting starts to cost more than reviewing. Spaced repetition software computes the next due date for you and serves the day’s stack. Anki, for instance, is built around cards the user writes themselves, which gives total control but demands real typing time.

The true cost of any such tool is card creation, not the learning curve of the interface. Most students give up during that step, not during the reviews. If you already have written lecture notes, look first for a way to turn those notes into cards instead of retyping them.

How does Study-Genie automate spaced repetition?

Study-Genie builds flashcards from your own document — PDF, Word, PowerPoint, a photo of handwritten notes, a recorded lecture, or pasted text — and then serves them back in spaced repetition. The cards cover your chapter rather than generic content, and you can export them to Anki if you would rather keep your own system. The free plan includes 10 flashcards and asks for no card details.

The same document also produces a structured study sheet and a quiz with adjustable difficulty, which gives you three different passes over the same material. In practice the sheet is for understanding, the flashcards for memorising, the quiz for checking. Premium (14.99 € per 28 days) and Ultimate (19.99 € per 28 days) open a weekly budget you spend freely across those formats, with no lock-in.