Description Level D Learning Goals Building on the addition skills up to +4 mastered in Level C, this level trains children in addition from +5 to +10 and addition with larger numbers, aiming to strengthen the essential mental arithmetic skills needed for calculation. Book (Volume/Month) - Week - Learning Content Book D1, Weeks 1–4: Addition +5: (1~9)+5, (1~14)+5, (1~19)+5 Addition +6: (1~9)+6, (1~13)+6, (1~19)+6 Achievement Test Book D2, Weeks 1–4: Addition +7: (1~9)+7, (1~19)+7, (1~23)+7 Addition +8: (1~9)+8, (1~19)+8, (1~22)+8 Achievement Test Book D3, Weeks 1–4: Addition +9: (1~9)+9, (1~15)+9, (1~21)+9 Addition +10: (1~9)+10, (1~15)+10, (1~20)+10 Achievement Test Book D4, Weeks 1–4: Comprehensive Addition +5 to +10: Numbers up to 19 + (5~6), Numbers up to 19 + (7~8), Numbers up to 19 + (9~10), Numbers up to 19 + (5~10) Larger Number Addition Achievement Test Book D5, Weeks 1–4: Larger Number Addition: Sums up to 15, Sums up to 20, Sums up to 25, Sums up to 30, Sums up to 35, Sums up to 40 Comprehensive Addition Review (Level D) Final Test