Study Guide — 2.OA.C.3
Determine whether a group of objects (up to 20) has an odd or even nu…
Add and subtract within the grade-level range using strategies and models.
What this standard means
- Determine whether a group of objects (up to 20) has an odd or even number of members, e.g., by pairing objects or counting them by 2s; write an equation to express an even number as a sum of two equal addends.
- Apply determine whether a group of objects (up to 20) has an odd or even nu… with models and explanation
- Adds and subtracts accurately in range
_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. Draw number bonds or number lines 2. Relate addition and subtraction as inverse operations 3. Check subtraction with addition
_See printable PDF for diagram._
Common mistakes
- Subtracting the smaller from the larger digit regardless of place
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 2.OA.C.3.
- [ ] Adds and subtracts accurately in range
- [ ] Uses a model or strategy
- [ ] Checks answers when possible
Materials for this standard
- Practice Problems — 20 printable sets
- Review — 10 difficulty levels
- Practice Test — 10 difficulty levels
- Answer key — for parents and tutors