Spaced repetition

Each move in your repertoire has its own review history: when you last reviewed it, how difficult it has been for you, when it is due again, and so on. We use this to decide when you should next see that move, so you're seeing the moves you're likely to forget soon, but not getting overwhelmed by moves that are already easy for you.

Playing a sound move that isn't in your repertoire can still count as a missed review. See Soft fails for how Chessbook separates chess quality from repertoire recall.

What version of spaced repetition does Chessbook use?

Our system is based on FSRS, the best open-source spaced repetition system, and arguably the best spaced repetition system overall. This is a much more modern system than SM-2, an algorithm developed in 1987 which Chessable's MoveTrainer is based on.

How does spaced repetition work if I have multiple repertoires?

Move progress is shared between repertoires, so if you play 1.e4 in three different places that progress will be shared.