Description Level E Learning Objectives Building on the basic mental arithmetic skills developed in Level D, students learn basic subtraction up to minus 10. Through the addition and subtraction practiced so far, this level aims to help students complete their mental arithmetic abilities. Book (Volume/Month) — Week — Learning Content E1: Weeks 1-4 Understanding Subtraction (Subtracting the Smaller Number, 1) 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 Subtraction from Numbers 11~12 Subtraction from Numbers 13~14 Subtraction from Numbers 15~16 Subtraction from Numbers up to 16 Comprehensive Achievement Test E4: Weeks 1-4 Subtraction from Numbers 17~19 Subtraction from Numbers 20~22 Subtraction from Numbers 23~25 Subtraction from Numbers up to 25 Comprehensive Achievement Test E5: Weeks 1-4 Comprehensive Review of Addition and Subtraction (Levels C~E) Final Test