Midcontinent Research for Education and Learning
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Common Core Mathematics K2
Cluster
Understand and apply properties of operations and the relationship between addition and subtraction.
Grade 1
1.OA.3.
Apply properties of operations as strategies to add and subtract.[Students need not use formal terms for these properties.] Examples: If 8 + 3 = 11 is known, then 3 + 8 = 11 is also known. (Commutative property of addition.) To add 2 + 6 + 4, the second two numbers can be added to make a ten, so 2 + 6 + 4 = 2 + 10 = 12. (Associative property of addition.)
1.OA.4.
Understand subtraction as an unknownaddend problem.
For example, subtract 10 − 8 by finding the number that makes 10 when added to 8.