The Leitner system explained: learning with piles

The Leitner system is one of the smartest ways to learn with flashcards, and it has been around since the 1970s. The idea from German science journalist Sebastian Leitner is simple: cards you find difficult, you practise often; cards you know, less and less. That way, all your study time goes on exactly the material that needs it. And all you need for it is some cards and a few rubber bands.

How it works

You divide your flashcards into piles, usually three to five. Each pile has its own repetition rhythm:

• Pile 1: every day. All new cards start here, and this is where the cards you got wrong end up.
• Pile 2: every other day. Cards you got right in pile 1.
• Pile 3: twice a week. Cards you got right again in pile 2.
• Pile 4: once a week. The cards you basically just know.

There are only two rules. If you get a card right, it moves up a pile. If you get it wrong, it goes back to pile 1, however far along it already was. Strict, but that's where the strength lies: a card only counts as known when you've got it right several times, spread over several days.

Why this works so well

The system combines two things that have long been known to strengthen memory. First, testing yourself: every card is a mini-test, and pulling the answer out of your memory is exactly the exercise that fixes knowledge in place. Second, spacing: because the piles have fixed rhythms, you automatically repeat the material spread out over days, with longer and longer gaps the better you know something. You don't have to think about what to revise today; the system decides for you. That saves not only time, but also the nagging feeling that you might be learning the wrong thing.

How to set it up in practice

A proper Leitner box with compartments is nice, but not necessary. Three or four piles with a rubber band round each and a note (daily, every other day, weekly) work just as well. Put them in a fixed spot on your desk, and you'll literally bump into them. Start simple: pick one subject for your next test, make the cards and start with everything in pile 1. After a few days you'll see the piles shifting by themselves, and that's secretly motivating too: you can see your knowledge growing.

When should you start?

The system needs time to do its job, because its strength lies in the days between repetitions. Two weeks before the test is ideal; one week is just about enough. Starting the night before makes little sense; you're better off simply going through the whole pile a few times. The great thing is that the daily time investment stays small: pile 1 gets thinner by itself as you learn more, so on most days you're done in ten minutes.

For the enthusiast: test-week level

If you're revising several subjects at once, give each subject its own colour of cards and keep one set of piles. Then every day you automatically practise a mix of subjects, and that variety helps your memory too. That way, a test week doesn't become a mountain, but a daily quarter of an hour with your piles.

Read also: Making flashcards: how to do it properly and Spaced repetition: learning smarter by spreading out your study