Boxes and Intervals: The Leitner Layout — Dux AI — Spaced Repetition Study Routine

The Leitner system is a simple implementation of spaced repetition where flashcards are sorted into groups reviewed at increasing intervals; here is what happens to a card in each box.

The Leitner system of the 1970s sorts flashcards into groups reviewed at increasing intervals. Each group is a box, and the box a card sits in determines how often you will see it: the first box is reviewed most often, later boxes less often.

The movement rule has two branches. Correctly answered cards are advanced to the next, less frequent box; incorrectly answered cards return to the first box. There is no third outcome, which is what keeps the layout self-correcting.

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Because cards that are answered wrongly return to the most frequent review box, difficult material is seen more often. A card that keeps failing will keep appearing in the daily session until you answer it correctly and it advances.

Set up the layout before your first session: label each box, write its review frequency next to it, and keep the table visible. The table is the contract that tells you where every card goes after each answer.

The number of boxes is a layout choice, not a rule of the method. What matters is that each box reviews less often than the one before it, so that the intervals increase as the cards advance.

Box 1 — reviewed most often; wrong answers land here.
Box 2 — reviewed less often than Box 1; correct answers from Box 1 arrive here.
Box 3 — reviewed less often than Box 2.
Later boxes — each reviews less often than the box before it.
Any box — a wrong answer sends the card back to Box 1.