2.OA.B.2 — Fluently Add and Subtract Within 20

Fluently add and subtract within 20 using mental strategies. By end of Grade 2, know from memory all sums of two one-digit numbers.

Students solve addition problems within 20 without needing to write every step. They use efficient thinking strategies such as making ten, doubles, and counting on to find answers mentally.

Students solve subtraction problems within 20 by thinking flexibly rather than relying only on objects or fingers. They may use strategies such as thinking of related addition facts, counting back, or finding the difference.

Fluency means students can solve facts accurately, efficiently, and with confidence. The goal is not just speed, but choosing strategies that become automatic through repeated practice and understanding.

By the end of Grade 2, students should recall all sums of two one-digit numbers without needing to count or reason them out each time. This memory foundation supports later work with larger numbers and more complex operations.