Spaced Repetition

Hermann Ebbinghaus discovered the forgetting curve in 1885 — memory decays exponentially unless you review at increasing intervals. Spaced repetition systems (SRS) like Anki exploit this by showing you flashcards right before you'd forget them. Medical students swear by it for memorizing thousands of drug interactions. Research shows spaced repetition produces 200% better long-term retention than massed practice. The optimal intervals: 1 day, 3 days, 7 days, 21 days, then monthly.