standard_description: Mentally add 10 or 100 to a given number 100–900, and mentally subtract 10 or 100 from a given number 100–900.
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