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Common Core Math2nd GradeOperations & Algebraic Thinking

2.OA.1: Solve Addition and Subtraction Word Problems

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

Make 2.OA.1 Word ProblemsAll 26 2nd Grade Math Standards

The Official Wording

Use addition and subtraction within 100 to solve one- and two-step word problems involving situations of adding to, taking from, putting together, taking apart, and comparing, with unknowns in all positions, e.g., by using drawings and equations with a symbol for the unknown number to represent the problem.

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

What 2.OA.1 Means in Plain English

Second graders read a story like “Mr. Diaz needs 60 chairs, has 25 set up, and a helper brings 18 more. How many more does he need?” and find the missing part. The numbers stay within 100, and the unknown can be the start, change or result.

Drawings and a symbol for the unknown, like 43 + ? = 60, do the heavy lifting. Students who can hold two steps in order are ready for 3.OA.8, where word problems use all four operations and an estimate checks the answer.

2.OA.1 I Can Statements

  • I can solve a two-step word problem within 100.
  • I can find the unknown wherever it hides in the story.
  • I can write an equation with a symbol for the unknown.

2.OA.1 Worked Example

A two-step chair problem with the unknown at the end, worked the way a confident 2nd grader talks through it.

Problem

Mr. Diaz needs 60 chairs for the assembly. He has set up 25. A helper brings 18 more. How many more chairs does he still need?

Two steps, one unknown
  1. Read it twice and find the question: how many more does he still need? That is the unknown.25 + 18 + ? = 60
  2. Step one: put together the chairs that are already there.25 + 18 = 43
  3. Step two: the unknown is the missing part. Draw a bar with 60 as the whole and 43 as the part he has.43 + ? = 60
  4. Count up from 43 to the next ten, then on to 60.43 + 7 = 50, 50 + 10 = 60, so 7 + 10 = 17
Answer17 more chairs

Check it: Add all three parts: 25 + 18 + 17 = 60, exactly the chairs he needs. The answer fits the story.

Common Mistakes with 2.OA.1

Grabbing the two numbers and adding

25 + 18 = 43, so he needs 43 chairs

Try this: Find the question first, then draw a bar model with 60 as the whole and point to the part that is unknown.

Stopping after step one

Writes 25 + 18 = 43 and circles 43 as the answer

Try this: Reread the question after every equation and ask whether it has been answered yet. Two steps means two equations before the circle.

Keyword hunting

“More” means add, so 43 + 60 = 103 chairs

Try this: Act the story out with counters or a drawing instead of hunting for keywords. In a compare or missing-part story, “more” often means subtract.

Where 2.OA.1 Fits

Comes Before1.OA.1Add and subtract within 20 to solve one-step word problems with the unknown in any position.1.OA.2Add three whole numbers to solve a word problem.
Alongside2.OA.2Know the facts within 20 that every word problem leans on.2.NBT.5Add and subtract within 100 with place-value strategies.2.MD.5Solve word problems about lengths within 100.
Comes Next3.OA.8Solve two-step word problems with all four operations, and check with an estimate.3.OA.3Solve multiplication and division word problems within 100.

Practice 2.OA.1

Word Problem GeneratorFree ToolAdding-to, taking-from and compare stories within 100, one and two steps, with the unknown moved around. Ask students to write the equation with a box for the unknown before solving.Grade 2Two-stepWithin 100
Make Word Problems

Quick Check

  1. Lena has 34 marbles. Her cousin has 19 fewer. How many marbles does her cousin have?
  2. A bus had 46 riders. Some got off at the mall, and 28 were left. How many got off?
  3. Ms. Reyes bought 52 pencils. She gave 24 to her class and then 13 to another teacher. How many pencils does she have left?

2.OA.1: Other Names

2.OA.12.OA.A.1CCSS.MATH.CONTENT.2.OA.A.1

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.