options: 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.)

Understand subtraction as an unknown-addend problem. For example, subtract 10 – 8 by finding the number that makes 10 when added to 8.
problem_activity: Narrative
The purpose of this activity is for students to choose from activities that focus on adding and subtracting within 10. Students choose from any stage of previously introduced centers and are encouraged to choose the center that will be most helpful for them at this time.
What’s Behind My Back
Check it Off
Five in a Row: Addition and Subtraction
Find the Pair
Required Materials
Materials to Gather
Materials from previous centers
Required Preparation
Gather materials from previous centers:
What's Behind My Back, Stage 2
Check it Off, Stages 1 and 2
Five in a Row: Addition and Subtraction, Stages 1 and 2
Find the Pair, Stage 2
Launch
Groups of 2
“Now you are going to choose from centers we have already learned.”
Display the center choices in the student book.
“Think about what you would like to do.”
30 seconds: quiet think time
Activity
Invite students to work at the center of their choice.
10 minutes: center work time
Student Facing
Choose a center.
What’s Behind My Back
[IMG]
Check it Off
[IMG]
Five in a Row: Addition and Subtraction
[IMG]
Find the Pair
[IMG]
Activity Synthesis
“How has working on these center activities helped you build fluency with addition and subtraction?”


correct_option_index: 1