Missing Addend Word Problems Worksheets for 1st Grade

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Grade 1MathAddition & SubtractionCCSS 1.OA.A.1

Skill: Solving add-to and put-together stories where one part is unknown, within 20

Preview of the Missing Addend Word Problems printable worksheet
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Teaching tips and what to try next

Suited to first graders who already solve stories where the total is unknown in Addition Word Problems Within 20. Acting out one story with small toys makes the hidden change easy to see before moving to numbers alone. Equation-only practice is in Missing Addends Within 20, and taking away as a missing part is in Subtraction as an Unknown Addend.

10 versions, each with its own answer key

Same skill and layout, a fresh set of problems in every version, so children can keep practicing without repeating a page. Problems are not repeated between versions unless a skill has only a small number of possible problems (for example, the addition facts within 10).

Download all 10 versions (one PDF)All 10 answer keys (PDF)

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About this worksheet

Some stories tell you the start and the end, but not what happened in the middle. Ava has 6 shells, finds some more, and now has 13. How many did she find? These change-unknown stories are among the hardest addition problems for young children, and first graders are expected to solve them within 20. This first grade worksheet gives focused practice on just this kind of story.

The page has eight short stories. In seven of them, a group grows by an unknown amount: shells are found, birds land on a fence, children get on a bus. One story puts two groups together, red and blue crayons, and asks for the size of the unknown group. Each start number is from 2 to 12, the missing amount is from 2 to 9, and every total is 20 or less. Each story has a box for a picture or equation and a line for the answer. Each of the ten versions has new numbers and its own answer key.

How to use it: read a story together and ask, "What do we know, and what are we trying to find?" Children often add the two numbers they see, so have them check that the answer plus the start really makes the total. Writing an equation such as 6 + ? = 13, then counting on from 6 to 13, is a reliable strategy.

The answer key shows every answer with its unit. For the same idea without stories, try our Missing Addends Within 20 worksheet. For stories where the total is unknown, try our Addition Word Problems Within 20 worksheet.