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Common Core Math1st GradeOperations & Algebraic Thinking

1.OA.2: Add Three Numbers in Word Problems

Also written as 1.OA.A.2 and CCSS.MATH.CONTENT.1.OA.A.2 · Cluster: Represent and solve problems involving addition and subtraction.

Make Three-Number Word ProblemsAll 21 1st Grade Math Standards

The Official Wording

Solve word problems that call for addition of three whole numbers whose sum is less than or equal to 20, e.g., by using objects, drawings, and equations with a symbol for the unknown number to represent the problem.

Common Core State Standards, Grade 1, Operations & Algebraic Thinking · Read it at the source · Checked October 14, 2026

What 1.OA.2 Means in Plain English

First graders solve stories that put three amounts together, like 4 pencils on one table, 7 on the next and 6 on the last, with a total of 20 or less. They show it with cubes, a drawing or an equation with a box for the total.

The smart move is choosing which two numbers to add first: 4 and 6 make ten, so the 7 just goes on top. That choice comes from 1.OA.3. In 2nd grade students add up to four two-digit numbers at once (2.NBT.6).

1.OA.2 I Can Statements

  • I can add three numbers with a total up to 20.
  • I can look for two numbers that make ten first.
  • I can show a three-number story with a drawing or equation.

1.OA.2 Worked Example

A three-table pencil count where the order of adding is the whole trick.

Problem

Table 1 has 4 pencils. Table 2 has 7 pencils. Table 3 has 6 pencils. How many pencils are on the three tables in all?

Pencils on three tables
  1. Three tables, all pencils, and the question asks how many in all. That is putting together.4 + 7 + 6 = ?
  2. Look for two numbers that make ten. 4 and 6 do.4 + 6 = 10
  3. Now add the number that is left to the ten.10 + 7 = 17
  4. Write the whole equation with the total in the box.4 + 7 + 6 = 17
Answer17 pencils in all

Check it: Add in the order the story gives: 4 + 7 = 11, then 11 + 6 = 17. Same total, so the answer holds.

Common Mistakes with 1.OA.2

Adding only two of the numbers

4 + 7 = 11, and the 6 never gets used

Try this: Have students cross out each number in the story as it goes into the equation, so a leftover number is easy to spot.

Counting every object from 1

Draws 17 pencils, counts them one by one and lands on 16

Try this: Teach students to look for a ten first, then count on from it, instead of counting every object from 1.

Thinking the story order is fixed

“You can’t add the 6 first, it comes last.”

Try this: Solve the same story two ways on the board, in story order and ten first, and let the class see both totals are 17.

Where 1.OA.2 Fits

Comes BeforeK.OA.4Find the number that makes 10 with any number from 1 to 9.
Alongside1.OA.1Solve word problems within 20 with two numbers and the unknown anywhere.1.OA.3Add numbers in any order or grouping to make the work easier.
Comes Next2.NBT.6Add up to four two-digit numbers with place-value strategies.2.OA.1Solve two-step word problems within 100.

Practice 1.OA.2

Word Problem GeneratorFree ToolPut-together stories with three amounts and a total of 20 or less. Ask students to circle the two numbers they add first.Grade 1Three numbersSums to 20
Make Word Problems
Addition Worksheet GeneratorFree ToolBare three-number sums like 3 + 8 + 7, with an answer key, for practicing the ten-first habit without the reading.Three addendsSums to 20Answer key
Make a Worksheet

Quick Check

  1. Jo has 5 red beads, 2 blue beads and 5 yellow beads. How many beads does she have?
  2. Add 3 + 9 + 1.
  3. A class picked 7 leaves on Monday, 3 on Tuesday and 9 on Wednesday. How many leaves did they pick?

1.OA.2: Other Names

1.OA.21.OA.A.2CCSS.MATH.CONTENT.1.OA.A.2

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.