A proposed answer to an addition or subtraction problem within 20 can be verified by representing the quantities with objects, joining or separating the collections, and counting the result; the count must correspond to the claimed numeral. This builds one-to-one correspondence between quantities and numerals, supports noticing and correcting counting errors, and introduces checking through the inverse relationship between addition and subtraction without extending to abstract proofs or larger-number algorithms.
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Detailed Explanation: Check an answer with objects
To check an addition answer, use objects such as counters, blocks, or buttons.
Suppose the problem is:
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Make a group of 8 objects.
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Make a second group of 5 objects.
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Join the two groups.
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Count all the objects once, touching each object as you count:
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The objects make a group of 13. This matches the claimed answer, so is correct.
Learn by doing: Check an answer with objects
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Practice:
Picture Numbers - Adding - Picture to Number (Within 20)
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Download/Modify Free Grade 1 'Check an answer with objects' Worksheet
Print this free 'Check an answer with objects' worksheet to practice this skill away from the computer. Click 'Modify' to easily customize this worksheet to your exact needs.
This Worksheet Includes:
- Picture Numbers - Adding - Picture to Number (Within 20)
- Picture Numbers - Subtracting - Picture and Instruction to Number (Within 20)
- Picture Numbers - Subtracting - Picture and Instruction to Word (Within 20)
- Picture Numbers - Subtracting - Picture to Word (Within 20)
- Picture Numbers - Adding - Picture to Equation (Within 20)
- Picture Numbers - Adding - Picture to Equation (Within 10)
- Picture Numbers - Adding - Picture to Equation (Within 5)
- Picture Numbers - Adding - Picture to Number (Within 10)
Units Teaching This Skill
These adaptive units introduce, teach, or reinforce this skill (Check an answer with objects) through scaffolded problems that grow in difficulty as concepts are understood.