Skip to main content
Common Core Math2nd GradeOperations & Algebraic Thinking

2.OA.3: Odd and Even Numbers

Also written as 2.OA.C.3 and CCSS.MATH.CONTENT.2.OA.C.3 · Cluster: Work with equal groups of objects to gain foundations for multiplication.

Make an Odd and Even WorksheetAll 26 2nd Grade Math Standards

The Official Wording

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.

Common Core State Standards, Grade 2, Operations & Algebraic Thinking · Read it at the source · Checked October 14, 2026

What 2.OA.3 Means in Plain English

Second graders take up to 20 counters and decide whether the number is odd or even by pairing them up or counting by 2s. Fourteen counters make 7 pairs with none left, so 14 is even, a double of 7. Fifteen leaves one alone, so 15 is odd.

Writing the even number as two equal addends, 14 = 7 + 7, is the first taste of equal groups. The same cluster has students add up arrays (2.OA.4), and in 3rd grade the doubles become the twos facts of multiplication (3.OA.1).

2.OA.3 I Can Statements

  • I can pair up objects to tell if a number is odd or even.
  • I can count by 2s to check a group of up to 20.
  • I can write an even number as two equal addends.

2.OA.3 Worked Example

Fourteen dots in two rows, so the pairs stand in columns and the question “anyone left over?” answers itself.

2 groups of 7
Two rows of seven. Every dot in the top row has a partner directly below it and nobody is left over, so 14 is even. Count the columns by 2s: 2, 4, 6, 8, 10, 12, 14.
14 = 7 + 7

Fourteen students line up in two rows for a partner game, seven in each row. Everyone has a partner, so 14 is even. When a fifteenth student joins, one person has no partner: 15 is odd.

Common Mistakes with 2.OA.3

Looking at the wrong digit

“12 is odd because 1 is odd”

Try this: Pair up 12 counters so none are left over, then show that only the ones digit decides: 0, 2, 4, 6 and 8 mean even.

Any two addends will do

9 = 4 + 5, so 9 is even

Try this: Insist on equal addends: 4 and 5 are not the same, so 9 cannot be split into two equal groups and is odd.

Losing count by 2s

2, 4, 6, 8, 9, 10 ... so 13 came out even

Try this: Move the counters into pairs as the student counts by 2s, one pair per number, so the count and the pile stay matched.

Where 2.OA.3 Fits

Comes BeforeK.OA.3Break numbers to 10 into pairs, like 8 = 4 + 4.1.OA.6Doubles facts within 20.
Alongside2.OA.4Add up the equal rows of an array.2.NBT.2Skip-count by 5s, 10s and 100s.
Comes Next3.OA.1Read 2 × 7 as two groups of seven.3.OA.9Explain patterns in the tables, like why every double is even.

Practice 2.OA.3

Math Worksheet GeneratorFree ToolOdd-or-even sorting at the 2nd grade level: numbers to 20 with room to draw the pairs and write the double, plus an answer key.Grade 2Odd and evenAnswer key
Make a Worksheet

Quick Check

  1. Is 16 odd or even? How do you know?
  2. Write 18 as a sum of two equal addends.
  3. Priya has 11 socks in her drawer. Can she make pairs with no sock left out?

2.OA.3: Other Names

2.OA.32.OA.C.3CCSS.MATH.CONTENT.2.OA.C.3

Common Core State Standards © Copyright 2010. National Governors Association Center for Best Practices and Council of Chief State School Officers. All rights reserved. Official wording from the Common Core State Standards PDFs at corestandards.org, last checked October 14, 2026. The explanation, I can statements, example, mistakes and practice on this page are EMStudio’s own, written beside the official wording. They are not part of the standard.