Description Level C Learning Objectives Building on the number-writing skills learned in Level B, this level focuses on practicing addition of 1~4 to help children grasp the basic concept of addition. Book (Volume/Month) / Issue (Week) - Learning Content Book C1, Weeks 1~4: Understanding "plus 1" (the next number) — the next number and adding 1. Addition of 1: (1~9)+1, (1~14)+1, (1~19)+1, (1~25)+1, (1~30)+1, (1~60)+1, (1~70)+1, (1~80)+1, (1~99)+1, (1~200)+1, (1~999)+1. Achievement test. Book C2, Weeks 1~4: Understanding "plus 2." Addition of 2: (1~8)+2, (1~17)+2, (1~22)+2, (1~28)+2, (1~35)+2, (1~40)+2, (1~45)+2. Achievement test. Book C3, Weeks 1~4: Understanding "plus 3." Addition of 3: (1~9)+3, (1~16)+3, (1~19)+3, (1~26)+3, (1~29)+3, (1~32)+3, (1~36)+3. Addition problems that sum to 10. Achievement test. Book C4, Weeks 1~4: Addition of 4: (1~10)+4, (1~15)+4, (1~19)+4, (1~26)+4. Addition problems that sum to 10. Achievement test. Book C5, Weeks 1~4: Comprehensive review of addition up to 4: up to (1~6)+4, up to (1~9)+4, up to (1~16)+4, up to (1~19)+4. Final test.