Description Level E Learning Objectives Building on the basic mental arithmetic skills developed in Level D, students learn basic subtraction up to 10. Through continued practice of addition and subtraction, this level aims to complete the foundation of mental arithmetic. Volume (Book/Month) - Week (Week) - Learning Content Volume E1, Weeks 1~4 Understanding subtraction (subtracting smaller numbers) Subtracting 1: (1~12)-1 Subtracting 2: (1~13)-2 Subtracting 3: (1~15)-3 Practice up to (1~15)-3 Achievement Test Volume 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 Volume 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 Volume 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 Volume E5, Weeks 1~4 Complete review of addition and subtraction (Levels C~E) Final Test