What is spaced repetition?

Spaced repetition is a review schedule built around the forgetting curve: instead of cramming, you revisit each item at increasing intervals — a day later, then a few days, then weeks — timed to land just before you would have forgotten it.

Each successful recall strengthens the memory and pushes the next review further out, so material you know well stops eating your time while shaky items come back often. Over weeks this concentrates effort exactly where it's needed.

Echoling applies spaced repetition to the sentences you practise. Lines you struggle with resurface sooner; lines you nail are spaced further apart, so your review session always focuses on what you're about to forget rather than what you already know.