How SM-2 (SuperMemo 2) Works: The Spaced Repetition Algorithm Behind Wordrop
SM-2 is the spaced repetition algorithm developed by Piotr Woźniak in 1987 that calculates the optimal review interval for each vocabulary word individually. This guide explains the exact formula, step-by-step examples, and why Wordrop uses SM-2 to help people learn vocabulary permanently.
📅 Apr 20, 2026⏱ 14 min read
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