When will you forget this?

Flashcard apps schedule reviews with a fixed rule: get it right, wait twice as long. But how fast a thing fades depends on the thing and on you. This model learned that decay from 10.2 million real reviews, and was then tested on 1.3 million more from learners it had never seen. It schedules from what it learned.

Something you are learning

Times you recalled it — 4

Times you forgot it — 1

learned decay curve when Leitner would review you when the model would review you (90% recall)

Learned half-life

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the point where you are as likely to forget it as recall it

Leitner would wait

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Does the learned schedule actually predict better?

Held out by learner — no person's reviews appear in both training and test data, so nothing is scored on someone the model has already met. Lower error is better.