The Leitner system: studying flashcards with boxes
Five boxes, cards that move forward when you know them and back when you miss them: the Leitner system is the simplest form of spaced repetition. Here is how to set it up and run it.
Key points
- The Leitner system sorts flashcards into several boxes: the better you know a card, the less often its box is reviewed.
- The core rule: a card you get right moves forward one box; a card you miss goes back to box 1.
- A common five-box schedule: every day, every three days, every week, every two weeks, every month.
- It is spaced repetition on paper: apps do the same thing card by card, with intervals calculated automatically.
- Study-Genie generates flashcards from your own course, schedules them with spaced repetition and, in the mobile app, reminds you on days when cards are due.
What is the Leitner system?
The Leitner system is a way of organising flashcards into numbered boxes. Every card starts in box 1, which you review often. Each time you answer correctly, the card moves to the next box, which you review less often. When you get it wrong, it goes back to the start. As a result, you spend your time on what you do not know and very little on what you already do.
It was described in the 1970s by Sebastian Leitner, a German journalist and science writer, in a book about how to learn. Its appeal is that it is entirely physical: index cards, a few boxes or envelopes and a schedule. No screen, no account. That is why it is still widely used for language vocabulary and definitions.
How do you set up Leitner boxes?
To set up a Leitner system, take five boxes, envelopes or compartments and number them 1 to 5. Give each box a review frequency that gets longer. A common schedule is: box 1 every day, box 2 every three days, box 3 every week, box 4 every two weeks, box 5 once a month. Write the schedule on a sheet of paper and stick it above your desk.
These intervals are not a law; what matters is that they grow from one box to the next. If your test is ten days away, tighten them. For a full year of vocabulary, add a sixth box reviewed every two months.
- Box 1 — every day: new cards and missed cards.
- Box 2 — every three days.
- Box 3 — every week.
- Box 4 — every two weeks.
- Box 5 — once a month, after which the card can leave the system.
What does a Leitner review session look like?
A Leitner session starts by checking which boxes are due today on your schedule. For each card, you read the question, give your answer out loud or in writing, then flip the card. If the answer is right and complete, the card moves forward one box. If it is wrong or hesitant, it goes back to box 1. You do not touch boxes that are not due.
Example in French: the card “réussir” is in box 2. You say “to succeed”, which is right, so it moves to box 3 and you will not see it for a week. The card “1066: Battle of Hastings” is in box 3, but you hesitate on the year: it goes back to box 1 and returns tomorrow. That strict rule is the original one; a gentler variant only moves a missed card back by one box.
How do you write good cards for the Leitner system?
A good Leitner card asks one question with one short, checkable answer. “Define photosynthesis” is too broad; “What are the two products of photosynthesis?” is a good card. If you are unsure what the card is asking for, you cannot honestly decide whether your answer was right, and sorting cards between boxes stops meaning anything.
For maths or physics, put the formula with its context, not the bare formula: “Kinetic energy of an object with mass m and speed v?” For languages, write each direction on a separate card, because recognising a word and producing it are two different skills.
- One idea per card.
- An answer you can mark right or wrong without debate.
- An example or context rather than a copied definition.
- Both directions of a vocabulary word on two separate cards.
What are the limits of a paper Leitner system?
A paper Leitner system becomes heavy as the number of cards grows. Beyond a few hundred cards, box 1 overflows, the daily review takes too long and it gets hard to follow the schedule without mistakes. Writing every card by hand also takes a lot of time, often more than the reviewing itself.
It does not travel well either: the boxes stay on your desk, while short review moments tend to happen on the bus or between lessons. And nothing reminds you that a box is due if you forget to check the schedule. That is exactly what apps automate.
How do you use the Leitner principle with Study-Genie?
Study-Genie applies the Leitner principle without any boxes to manage. You upload your course (a PDF, a photo of notes, slides, a recording or text) and the app generates flashcards with one idea each, which you can edit, delete or add to. You can also write cards yourself, and those use no AI allowance. Reviews follow SM-2 spaced repetition: a missed card comes back soon, a known card moves further away.
In the iPhone and Android app you answer by swiping the card left or right, and a reminder can tell you on days when cards are due. Decks export to Anki if you want to keep them elsewhere. Every new account can try Essential free for 7 days with no card, then continue for €2 per 28-day cycle.
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Upload your course: Study-Genie turns it into flashcards and schedules them with spaced repetition, with reminders in the app.
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