🗓️ The 1-3-7-21 Spaced Repetition Schedule Review When Purpose Time R1 +1 day Catch what didn't encode at all 3 min R2 +3 days Rebuild the fading trace 4 min R3 +7 days Move into medium-term memory 4 min R4 +21 days Lock into long-term memory 4 min Rule: if you fail an item at any review, it goes back to R1. If you pass R4 twice, retire it to "Solid" and stop reviewing it.

A learner adding 7 new words and 7 new phrases per week reaches a steady state of about 12 minutes of daily revision — and never loses ground.

📦 The Three-Box Method Box 1 — Shaky 🔴 — you hesitate, guess, or get it wrong. Review daily. Box 2 — Warming 🟡 — correct but slow. Review every 3 days. Box 3 — Solid 🟢 — instant, automatic, used in real speech. Review monthly at most.

Move items up one box after two clean recalls, and straight back down to Box 1 after any failure. The asymmetry is deliberate — memory rewards honesty.