How the five-box Letterbox system works

The Letterbox is Mynawoo's spaced-repetition system, based on the Leitner method. It has five boxes. New words start in Box 1, which you review often.

Each correct answer promotes a card to the next box, where it is reviewed less frequently. A card you forget drops back to Box 1. Words that reach the top box are ones you know well.

Because review time grows as a word becomes familiar, you spend less time on easy words and more on difficult ones, which is the most efficient way to remember vocabulary long term.