Study Guide — K.OA.A.3

Decompose numbers to 10

Break numbers apart in different ways — 5 is 2+3 and also 4+1.

What this standard means

• Find two parts that make a number ≤ 10
• Find more than one decomposition for the same number
• Record with drawings or equations
• Use ten-frames to show parts

_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. Shake and spill counters on a ten-frame 2. Write all the ways to make 7 3. Use two colors to show parts

_See printable PDF for diagram._

Common mistakes

• Only one decomposition for each number
• Parts that don’t add to the whole
• Confusing parts with the total

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 K.OA.A.3.

• [ ] Two decompositions for numbers 2–10
• [ ] Records with equation or drawing
• [ ] Explains parts and whole

Materials for this standard

• Practice Problems — 20 printable sets
• Review — 10 difficulty levels
• Practice Test — 10 difficulty levels
• Answer key — for parents and tutors