Find the Missing Number (Within 20)
1.OA.8 — Determine the unknown whole number in an addition or subtraction equation with the unknown in any position
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What is on the three Find the Missing Number (Within 20) worksheets
- Support
- draws a number bond beside every problem.
- On level
- The grade's own level, with no drawings.
- Challenge
- uses the harder cases, and drops the familiar layout.
Example problems from the on-level sheet
- 6 + 9 = ___
- 13 - ___ = 8
- ___ - 2 = 6
Every sheet is generated, so the numbers are different each time you make one.
Before this: 1.OA.7 — understand the meaning of the equal sign; determine whether equations are true or false.