CCSS.Math.Content.K.OA.A.3
The Standard
Decompose numbers less than or equal to 10 into pairs in more than one way, e.g., by using objects or drawings, and record each decomposition by a drawing or equation (e.g., 5 = 2 + 3 and 5 = 4 + 1).
Common Core State Standards for Mathematics · Operations and Algebraic Thinking
Teacher's field guide
What This Standard Means
What Students Need to Do
- Students split a group of up to 10 objects into two smaller groups in more than one way. They show each split with objects, drawings, or equations.
What Mastery Looks Like
- A student can split a set of up to 10 objects in several ways without changing the total. They can record each split with a clear drawing or an equation such as 7 = 3 + 4.
Common Misconceptions
- Some students change the total while moving objects or count one object in both groups. Others only reverse a pair, such as 2 + 5 and 5 + 2, or forget that zero can be one part.
How to Assess It
- Give each student six counters. Ask them to show and record three different splits of six using drawings or equations.
Lesson moves
Ways to Teach It
Give each child eight counters and two cups, then have them find and draw every way to split the counters.
Ask, “How do you know you found all the ways to make six?” and have partners explain with drawings.
Play Make Ten Memory by matching numeral cards that combine to make ten, then record each matched pair as an equation.
Pack seven toy snacks into two lunch bags in different ways, and label how many snacks are in each bag.
Free download
Printable K.OA.A.3 Worksheet
A ready-to-print activity worksheet aligned to CCSS.Math.Content.K.OA.A.3, with an answer key for the teacher on its own page. No account needed.
PDF, US Letter, prints cleanly in black and white.
Download the worksheetLearning progression
Where This Standard Sits
See the whole path on the Operations & Algebraic Thinking progression map.
Before This Standard
If students are struggling here, check these first.
- CCSS.Math.Content.K.CC.B.5
Counting objects and making a set of a given size supports checking the total and parts in number decompositions.
- CCSS.Math.Content.K.CC.B.4
Decomposing 5 into parts requires knowing counted objects make a total quantity and that number names represent those quantities.
- CCSS.Math.Content.K.OA.A.1
Representing addition with objects, drawings, and equations supports showing number pairs that make the same total.
What This Unlocks
Mastery here sets students up for these next.
- CCSS.Math.Content.1.OA.B.4
Decomposing numbers into two parts supports seeing subtraction as finding the missing part in an addition pair.
- CCSS.Math.Content.1.OA.B.3
Decomposing numbers into pairs supports seeing addends as parts that can be rearranged or grouped in addition strategies.
- CCSS.Math.Content.K.OA.A.5
Knowing number pairs within 5 supports quick addition and subtraction facts by seeing parts and wholes instead of counting each time.
- CCSS.Math.Content.K.OA.A.4
Making 10 with a given addend is a special case of decomposing 10 into addend pairs.
Keep exploring
Related Standards
- CCSS.Math.Content.K.NBT.A.1
Compose and decompose numbers from 11 to 19 into ten ones and some further ones, e.g., by using objects or drawings, and record each composition or decompositio...
- CCSS.Math.Content.1.OA.C.6
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 + ...
- CCSS.Math.Content.4.NF.B.3b
Decompose a fraction into a sum of fractions with the same denominator in more than one way, recording each decomposition by an equation. Justify decompositions...
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