Spaced revision: how to stop forgetting what you studied

You studied a topic last month, and today it feels new. That is normal. In the 1880s, Hermann Ebbinghaus showed that memory fades fast at first and then more slowly. Each time you recall something, it fades more slowly than before.

The idea

Revise just as you begin to forget, with growing gaps. Research on spaced practice, including a large review by Cepeda and colleagues in 2006, supports this over cramming the same hours together.

A schedule you can follow

• Revise after 1 day
• then 3 days
• then 7 days
• then 15 days
• then 30 days

If you get it wrong at any step, go back to the start for that question.

Let the app do the counting

Tracking this on paper for hundreds of questions is hard. Score Delta uses this schedule: each practice question gets its next date from your answer, and your daily revision shows what is due today. Spend your energy on the questions, not on the calendar.