2.OA.B.2 — Fluently add and subtract within 20 using mental strategies.

What this standard asks students to do

2.OA.B.2 is a 2nd grade Common Core standard in the Operations & Algebraic Thinking strand. It asks students to: fluently add and subtract within 20 using mental strategies. Teachers typically address it during the add and subtract within 20 cluster, alongside the related standards listed below. FoxFish generates printable worksheets, auto-graded quizzes, and flashcard sets aligned to this standard in seconds.

Sample questions aligned to 2.OA.B.2

1. Example 1

   8 + 7 = ?

2. Example 2

   15 − 9 = ?

3. Example 3

   6 + 6 + 3 = ?

Want a full worksheet? Generate 20 problems aligned to 2.OA.B.2.

Common student mistakes

Build distractors and reteach prompts around the errors students actually make on this standard.

• 1Switching from a strategy to counting on fingers under timed pressure — fluency hasn't fully transferred.
• 2Confusing facts in the 'doubles plus one' family (e.g., 6 + 7 vs 7 + 7).
• 3Slow recall on subtraction facts even when addition is fluent (subtraction lags by 3–6 months).

Teacher FAQ

Related standards in this cluster

• 1.OA.C.6Add and subtract within 20 using mental strategies; demonstrate fluency for addition and subtraction within 10.

Teacher guides for 2.OA.B.2

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