Unit Plan 15 (Grade K Math): Decompose Numbers ≤10

Focus: Break numbers ≤10 into pairs in more than one way; record with drawings and equations.

Grade Level: K

Subject Area: Mathematics (Operations & Algebraic Thinking)

Total Unit Duration: 5 sessions (one week), 30–40 minutes per session

I. Introduction

Students explore how a whole can be broken into two parts in many ways. Using two-color counters, linking cubes, five/ten-frames, and number bonds, they model different pairs that make the same whole, then write matching equations (e.g., 7 = 3 + 4, 7 = 5 + 2). Emphasis is on connecting model → words → equation and noticing that the whole stays the same even when parts change.

Essential Questions

• How can I break a number into two parts in different ways?
• How do my model and my equation show the same decomposition?
• How do I know I’ve found all the ways to make a number?

II. Objectives and Standards

Learning Objectives — Students will be able to:

1. Decompose numbers ≤10 into two parts in more than one way using objects or drawings.
2. Record decompositions with equations using + and = (e.g., 6 = 1 + 5, 6 = 4 + 2).
3. Explain that different parts can make the same whole.
4. Match each number in an equation to parts/whole in a model (five/ten-frame, number bond).
5. Find a missing part when given a whole and one part (within 10).

Standards Alignment — CCSS Kindergarten (threaded across the unit)

• K.OA.3: Decompose numbers less than or equal to 10 into pairs in more than one way; record each decomposition by a drawing or equation.
• K.OA.1: Represent addition and subtraction with objects, drawings, and equations (supporting).
• Mathematical Practices: MP.2 (Reason abstractly & quantitatively) emphasized; MP.4, MP.6 threaded.

Success Criteria — Student Language

• I can show two (or more) ways to make a number.
• I can write an equation that matches my picture.
• I can tell which numbers are the parts and which is the whole.