In this unit, students put together their understanding from throughout the year to cap off the major work and fluency goals of the grade.

Section A: Add and Subtract within 20

In this section, students finalize their fluency with addition and subtraction within 10. Students do an inventory of addition and subtraction facts to identify the facts they are not yet fluent with. They are encouraged to continue working with those facts throughout the section. There is a focus on the relationship between addition and subtraction in order to help students recognize how knowing an addition fact allows them to also know the related subtraction facts. Students recognize how adding and subtracting fluently within 10 helps them add and subtract larger numbers as they work with numbers up to 20.

Section B: Story Problems

In this section, students revisit some of the different types of story problems that were introduced in previous units. They solve these problems in any way that makes sense to them. Students discuss how understanding the relationship between addition and subtraction is helpful when solving these problems. They also discuss methods for addition and subtraction that involve making a ten, which is helpful when working with numbers up to 20.

Section C: Numbers to 120

In this section, students organize, count, and represent groups of up to 120 objects using their understanding of place value. Students create multiple representations of two-digit numbers, demonstrating their understanding that the two digits in a two-digit number represent amounts of tens and ones and that numbers can also be composed of different amounts of tens and ones.

Try it at home!

Ask your first grader to list the addition and subtraction facts within 10, with which they are not yet fluent.

Questions that may be helpful as they share:

• Are there other facts that could help you with this fact?
• How can we represent this fact with pictures or objects?

Near the end of the unit, ask your first grader to solve these problems:

• Let’s count on/count back, starting at [a number 1–120].
• Let’s find objects in our home to count.

Questions that may be helpful as they work:

• How did you know which number comes next?
• What is a number less than ___? What is a number greater than ___?

Solution:
Answers may vary.

Sample response:

• I need more practice with \(9-3\). I can use \(3+5=8\) to help me. I know that 9 is 1 more than 8, so the answer will be 1 more than 5.
• I can draw 3 circles. Then I can draw more circles until I get 9 circles. I can show 9 cubes. Then I can take away 3.
• I know that 30 will come after 29 because I know that 10 comes after 9.
• 35 is less than 52. 70 is greater than 68.