options: Explain why addition and subtraction strategies work, using place value and the properties of operations. (Explanations may be supported by drawings or objects.)

Fluently add and subtract within 100 using strategies based on place value, properties of operations, and/or the relationship between addition and subtraction.

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

Add up to four two-digit numbers using strategies based on place value and properties of operations.

Add and subtract within 1000, using concrete models or drawings and strategies based on place value, properties of operations, and/or the relationship between addition and subtraction; relate the strategy to a written method. Understand that in adding or subtracting three-digit numbers, one adds or subtracts hundreds and hundreds, tens and tens, ones and ones; and sometimes it is necessary to compose or decompose tens or hundreds.
problem_activity: Narrative
The purpose of this activity is for students to choose from activities that focus on adding and subtracting or sorting and representing data.
Students choose from any stage of previously introduced centers.
What's Behind My Back?
How Close?
Number Puzzles
Sort and Display
Required Materials
Materials to Gather
Materials from previous centers
Required Preparation
Gather materials from:
What's Behind My Back, Stages 2 and 3
How Close, Stages
1–
3
Number Puzzles, Stages 1 and 2
Sort and Display, Stage 2
Launch
“Today you will choose from centers we have already learned.”
Display the center choices in the student book.
“Think about what you would like to do first.”
30 seconds: quiet think time
Activity
Invite students to work at the center of their choice.
10 minutes: center work time
"Choose what you would like to do next."
10 minutes: center work time
Student Facing
Choose a center.
What's Behind My Back?
[IMG]
How Close?
[IMG]
Number Puzzles
[IMG]
Sort and Display
[IMG]
Activity Synthesis
“Which activity did you choose? What did you like about the activity you chose?”


correct_option_index: 1