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

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.

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

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 the center activity that will most help them build their fluency for addition and subtraction within 100. These two centers were introduced in previous units and focus on adding and subtracting within 100:
Five in a Row
Target Numbers
Required Materials
Materials to Gather
Materials from a previous activity
Materials from previous centers
Required Preparation
Each group of 2 needs access to the cards used in the previous activity.
Gather materials from previous centers:
Five in a Row, Stage 6
Target Numbers, Stages 3
–
5
Launch
Groups of 2
“Now you will choose from different center activities we learned. You may also choose to continue with Heads Up.”
Display the student page.
“Think about which activity 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
“Think about what center you would like to do now.”
30 seconds: quiet think time
Invite students to work at the center of their choice.
10 minutes: center work time
Student Facing
Choose a center.
Five in a Row
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Target Numbers
[IMG]
Activity Synthesis
“What did you like about the activities you worked on today?”


correct_option_index: 3