NC.K.OA.3
Decompose numbers less than or equal to 10 into pairs in more than one way using objects or drawings, and record each decomposition by a drawing or expression.
Embedded Files
Step 1: Lesson Standards & Learning Goals
In this standard, students decompose (break apart) numbers less than or equal to 10 into two addends in multiple ways. All of this work should be done with objects or drawings, and each decomposition should be represented with either drawings, a verbal expression, or when students are ready, a written expression. The focus of this standard is that a number can be broken into different pairs of two smaller numbers. Students should have multiple experiences exploring how a number can be broken into two smaller numbers using objects such as 2-color counters or breaking up snap cubes. This standard intersects with NC.K.OA.2 and the both addends unknown problem type.
By the end of the year, kindergarten students are expected to fluently add or subtract within 5 (NC.K.OA.5), which means that they should be able to recall from memory all of the ways to decompose numbers that are 5 or less into 2 equal addends within 5 seconds. When developing students’ fluency, flashcards and other activities, such as the repetitive writing of number bonds and equations, are not as effective as math games and activities that promote students’ work with the relationships between numbers (Kling & Bay-Williams, 2020). As students use concrete objects and drawings to explore these relationships, they discover all of the pairs or “partners” that compose a number. Through these experiences, students discover number relationships and begin to internalize addition/subtraction facts and develop fluency.
In kindergarten, students need ample experiences breaking apart numbers and using the vocabulary “and,” “joined with” and “same amount as” before symbols (+, =) and equations (5 = 3 + 2) are introduced. If equations are used, a mathematical representation (picture, objects) needs to be present as well.
Sample Essential Questions
Sample Essential Questions
How can we break apart a number into two smaller numbers?
Why is it important to be able to break numbers into different parts?
What strategies can we use to decompose numbers?
How can we represent different decompositions of a number using drawings or objects?
How does decomposing numbers help us solve addition and subtraction problems?
How can you show different ways to break the number 7 into pairs?
How can we use what we know about decomposing numbers to help us add and subtract?
What patterns do you notice when decomposing different numbers?
How can we check if our decompositions are correct?
Explain your thinking when decomposing numbers in different ways.
How can numbers be decomposed?
How do two parts make a whole?
Vocabulary
Vocabulary
addends
break apart
combinations
decompose
expression
equation (based on readiness)
pairs
part
part-part-whole
representation
strategy
whole
Students will be able to...
Students will be able to...
Use concrete objects to decompose numbers into pairs or partner numbers.
Represent addition and subtraction problems using concrete objects, drawings, or verbal expressions.
Explain their reasoning for how they decomposed the number.
Explain how decomposing numbers help with addition and subtraction.
Students will know...
Students will know...
Decompose means to break apart.
Numbers can be decomposed in multiple ways.
There are multiple strategies that can be used to decompose numbers.
There is a relationship between adding and subtracting.
Step 2: Assessment
NCDPI Math Assessment Released Forms
Grade K Math Assessment Practice Prompts
Grade K Released Summative Assessments
Step 3: Lesson Instructions
Possible Activating Strategies
Possible Activating Strategies
Teacher Resources
Teacher Resources
Tools for NC Teachers
Cluster 6 - Lessons
Math Expressions - (Barnes and Hearne)
Motivation Math
Think Up! Math
Eureka Math/Engage NY Resources
Embarc Online (Eureka Math)
Topic A: Composition and Decompositions of 2, 3, 4, and 5
Topic B: Decompositions of 6, 7, and 8 into Number Pairs
Topic E: Decompositions of 9 and 10 into Number Pairs
Topic H: Patterns with Adding 0 and 1 and Making 10
Zearn Math - Online Support Practice for Eureka Math (Requires free account)
North Carolina Collaborative for Mathematics Learning - Kindergarten Instructional Framework
NCDPI Resources
Kindergarten Math Assessment Practice Prompts
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