Description Level E Learning Objectives Building on the basic mental arithmetic skills developed in Level D, this level focuses on learning basic subtraction up to 10. Through continued practice of both addition and subtraction learned so far, children work toward mastering solid mental math skills. Book (Volume/Month) Week Learning Content E1 Weeks 1–4 Understanding subtraction (subtracting smaller numbers) Subtraction 1: (1~12)-1 Subtraction 2: (1~13)-2 Subtraction 3: (1~15)-3 Practice up to (1~15)-3 Achievement Test E2 Weeks 1–4 Subtracting 4–10 (1~15)-4, (1~15)-5, (1~15)-6, (1~15)-7, (1~15)-8, (1~15)-9, (1~15)-10 Practice up to (1~15)-10 Achievement Test E3 Weeks 1–4 Subtracting from numbers 11–12 Subtracting from numbers 13–14 Subtracting from numbers 15–16 Subtracting from numbers up to 16 Comprehensive Achievement Test E4 Weeks 1–4 Subtracting from numbers 17–19 Subtracting from numbers 20–22 Subtracting from numbers 23–25 Subtracting from numbers up to 25 Comprehensive Achievement Test E5 Weeks 1–4 Complete review of addition and subtraction (Levels C–E) Final Test