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Common Core Math1st GradeOperations & Algebraic Thinking

1.OA.5: Relate Counting to Adding and Subtracting

Also written as 1.OA.C.5 and CCSS.MATH.CONTENT.1.OA.C.5 · Cluster: Add and subtract within 20.

Make a Number Line to 20All 21 1st Grade Math Standards

The Official Wording

Relate counting to addition and subtraction (e.g., by counting on 2 to add 2).

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

What 1.OA.5 Means in Plain English

First graders see that adding 3 is just counting on three more, and taking 2 away is counting back two. For 9 + 3 a child holds 9 in their head and says “10, 11, 12”, tapping one finger for each word.

Counting on replaces counting all, the kindergarten habit of counting every object from 1. It is the first strategy in the fluency work of 1.OA.6, and in 2nd grade it grows into counting on by tens and ones within 100 (2.NBT.5).

1.OA.5 I Can Statements

  • I can count on from a number to add.
  • I can count back from a number to subtract.
  • I can start counting at the bigger number.

1.OA.5 Worked Example

One fact counted on and its partner counted back, with the finger-tracking that keeps the count honest.

Problem

Solve 8 + 3 by counting on. Then solve 11 - 3 by counting back.

Counting on 3, then counting back 3
  1. Start at the bigger number and keep it in your head. There is no need to count up to 8.8
  2. Count on three more, putting up one finger for each number you say.9, 10, 11
  3. Three fingers are up, so the counting stops. The last number said is the sum.8 + 3 = 11
  4. Now go backward. Start at 11 and count back three, one finger for each.10, 9, 8
  5. The last number said is what is left.11 - 3 = 8
Answer8 + 3 = 11 and 11 - 3 = 8

Check it: Counting on 3 and counting back 3 are opposite moves, so together they bring you back to where you started: 8.

Common Mistakes with 1.OA.5

Counting all from 1

For 8 + 3, counts out 8 fingers, then 3 more, then counts all 11

Try this: Hide the first group under a cup, write 8 on the cup, and count on from the cup: 9, 10, 11.

Saying the start number in a count back

11 - 3: “11, 10, 9”, so 9

Try this: Use a number line where each count is a hop: the first hop back from 11 lands on 10, so 11 is never counted.

Losing track of how many were counted

9 + 4: “10, 11, 12, 13, 14”, one count too many

Try this: Tap one finger for each number said and stop the moment the fingers show the number being added.

Where 1.OA.5 Fits

Comes BeforeK.CC.2Count forward from any number, not just from 1.K.CC.4Know that each next number name means one more.
Alongside1.OA.6Add and subtract within 20, with counting on as one strategy.1.NBT.1Count to 120 starting from any number.
Comes Next2.NBT.5Add and subtract within 100, counting on by tens and ones.2.OA.2Add and subtract within 20 with mental strategies that go beyond counting.

Practice 1.OA.5

Number Line GeneratorFree ToolA 0 to 20 number line with every number labeled, for finger hops forward to add and backward to subtract.0 to 20Step 1Labeled
Make a Number Line
Addition Worksheet GeneratorFree ToolFacts that add 1, 2 or 3, like 9 + 2 and 3 + 8, so counting on is always faster than counting all.Add 1, 2, 3Within 20Answer key
Make a Worksheet

Quick Check

  1. Count on to solve 7 + 2.
  2. Count back to solve 13 - 3.
  3. Jada has 6 stickers in her book and gets 3 more. Which number should she start counting from, and what does she say?

1.OA.5: Other Names

1.OA.51.OA.C.5CCSS.MATH.CONTENT.1.OA.C.5

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.