1.OA.C.6 — Add and subtract within 20 using mental strategies; demonstrate fluency for addition and subtraction within 10.
Cluster: Add and subtract within 20
What this standard asks students to do
1.OA.C.6 is a 1st grade Common Core standard in the Operations & Algebraic Thinking strand. It asks students to: add and subtract within 20 using mental strategies; demonstrate fluency for addition and subtraction within 10. 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 1.OA.C.6
- Example 1
9 + 6 (use a make-a-10 strategy).
- Example 2
14 − 8 = ?
- Example 3
Find 7 + 7 + 1.
Want a full worksheet? Generate 20 problems aligned to 1.OA.C.6.
Common student mistakes
Build distractors and reteach prompts around the errors students actually make on this standard.
- 1Counting all instead of counting on (e.g., for 8 + 3, restarting from 1 instead of from 8).
- 2Not using doubles or near-doubles facts strategically (e.g., 7 + 8 as 7 + 7 + 1).
- 3Memorizing without strategy — fluency drops as soon as the problem looks unfamiliar.
Teacher FAQ
What does 'fluency within 10' mean in first grade?
Students answer addition and subtraction facts within 10 accurately, efficiently, and flexibly — typically within 3 seconds — and can explain the strategy they used.
Related standards in this cluster
Teacher guides for 1.OA.C.6
Keep exploring
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