standard_description: 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.)
problem_activity: Stage 2: Add and Subtract within 20
Required Preparation
Materials to Copy
Blackline Masters
Compare Stage 2 Addition Cards to 20
Compare Stage 2 Subtraction Cards to 20

Narrative
Students use cards with addition and subtraction expressions within 20.


aligns: no