Learning Curves — Memory, Forgetting & Spaced Repetition

Algorithm:

Initial Stability S₀ (days): 1.0 Review Quality (0–5):

Retention at Day 30—

Reviews Scheduled0

Current Stability—

Time Savings vs Massed—

Ebbinghaus
R(t) = e^−t/S
SM-2: I_n = I_n-1 · EF, EF=2.5
Optimal interval: I = S · ln(1/0.9)