standard_description: Understand that the two digits of a two-digit number represent amounts of tens and ones. Understand the following as special cases:
- The numbers from 11 to 19 are composed of a ten and one, two, three, four, five, six, seven, eight, or nine ones.
- The numbers 10, 20, 30, 40, 50, 60, 70, 80, 90 refer to one, two, three, four, five, six, seven, eight, or nine tens (and 0 ones).
- 10 can be thought of as a bundle of ten ones — called a “ten.”
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