Study Guide — 1.OA.C.6
Add and subtract within 20, demonstrating fluency for addition and su…
Build quick recall of facts within the grade-level range.
What this standard means
- Add and subtract within 20, demonstrating fluency for addition and subtraction within 10. Use strategies such as counting on; making ten (e.g., 8 + 6 = 8 + 2 + 4 = 10 + 4 = 14); decomposing a number leading to a ten (e.g., 13 - 4 = 13 - 3 - 1 = 10 - 1 = 9); using the relationship between addition and subtraction (e.g., knowing that 8 + 4 = 12, one knows 12 - 8 = 4); and creating equivalent but easier or known sums (e.g., adding 6 + 7 by creating the known equivalent 6 + 6 + 1 = 12 + 1 = 13).
- Apply add and subtract within 20, demonstrating fluency for addition and su… with models and explanation
- Solves facts with strategies or recall
_See printable PDF for diagram._
How to use the 20 practice sets
| Sets | When to use | | --- | --- | | 1–5 | Intro — explore together, short written items | | 6–10 | Core skills — diagrams and written practice | | 11–15 | Mixed review — explain thinking | | 16–20 | Stretch — word problems and mastery tasks |
Pacing: 10–15 minutes per session.
How to practice
1. Short daily practice — 5 minutes 2. Mix oral and written facts 3. Celebrate strategy use, not just speed
_See printable PDF for diagram._
Common mistakes
- Finger counting on every fact
- Guessing without checking
Review and practice tests
1. Start Review 1/10 when sets 1–3 feel comfortable. 2. Move up one review level with little help. 3. Use Practice Test 4/10–6/10 for mid-standard checks. 4. Practice Test 10/10 is the mastery bar for 1.OA.C.6.
- [ ] Solves facts with strategies or recall
- [ ] Explains one strategy used
- [ ] Accuracy improves over the 20 sets
Materials for this standard
- Practice Problems — 20 printable sets
- Review — 10 difficulty levels
- Practice Test — 10 difficulty levels
- Answer key — for parents and tutors