Spaced repetition: the science-backed way to revise

What is spaced repetition?

Spaced repetition is reviewing material at increasing intervals: today, in 3 days, in a week, in two weeks, in a month. Each successful recall moves the next review further into the future. Each failed recall resets it.

Why does it work? Hermann Ebbinghaus's forgetting curve shows that we lose roughly half of new information within a day. But each well-timed review flattens that curve dramatically — until the information is essentially permanent.

How to use spaced repetition for revision

Option 1 — Apps (easiest)

Anki and Quizlet do the maths for you. You make flashcards, mark each one easy/medium/hard, and the algorithm schedules the next review. Anki is free and brutally efficient; Quizlet is friendlier.

Option 2 — The Leitner system (paper)

You don't need an app. Get five small boxes labelled 1 to 5:

1. All new flashcards start in Box 1.
2. Box 1 cards are reviewed every day.
3. If you get a card right, it moves up one box.
4. If you get it wrong, it goes back to Box 1.
5. Review Box 2 every 2 days, Box 3 every 4 days, Box 4 every week, Box 5 every two weeks.

It's mechanical, it's annoying for the first week, and then it just works.

Option 3 — A spreadsheet or notebook

For topics rather than facts, list every spec point in a spreadsheet. Add columns for "last reviewed" and "confidence". Each week, sort by confidence and oldest review date — and tackle the worst offenders first.

How to combine it with active recall

Spaced repetition and active recall are best friends. Active recall is the act of forcing your brain to retrieve. Spaced repetition is the schedule for when to do it. You need both.

Practical workflow:

1. Learn a topic (read, watch, take messy notes)
2. Within 24 hours, do an active-recall pass on it
3. Schedule reviews at 3 days, 1 week, 2 weeks, 1 month
4. Each successful review extends the interval

Mistakes to avoid

• Cramming a thousand new cards in one day. The algorithm will punish you next week. Add 10–20 new cards per day.
• Skipping reviews. Miss a week and the algorithm loses its calibration. Better to do 15 minutes daily than 2 hours on Saturday.
• Cards that are too long. One fact per card. Break essays into atomic chunks.
• Using it for everything. Spaced repetition is excellent for facts, dates, vocabulary, formulas. It's bad for essay-writing skill — for that, write essays.

How My Study Diary helps

My Study Diary doesn't replace Anki — it sits alongside it. The diary tracks how much time you've spent revising each subject so you can spot subjects that haven't been touched in a fortnight (the ones spaced repetition would tell you to prioritise next).

Open the diary and try it for a week.