options: Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used.

Add within 100, including adding a two-digit number and a one-digit number, and adding a two-digit number and a multiple of 10, 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 and explain the reasoning used. Understand that in adding two-digit numbers, one adds tens and tens, ones and ones; and sometimes it is necessary to compose a ten.

Subtract multiples of 10 in the range 10-90 from multiples of 10 in the range 10-90 (positive or zero differences), 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 and explain the reasoning used.
problem_activity: Narrative
The purpose of this activity is for students to choose from activities focusing on two-digit numbers. Students are introduced to stage 6 of the Five in a Row center. Then students choose between that center or others previously introduced.
Students choose from any stage of previously introduced centers.
Five in a Row
Get Your Numbers in Order
Grab and Count
Required Materials
Materials to Gather
Materials from previous centers
Paper clips
Two-color counters
Materials to Copy
Five in a Row Addition and Subtraction Stage 6 Gameboard
Required Preparation
Gather materials from previous centers:
Five in a Row, Stages 1-6
Get Your Numbers in Order, Stage 1
Grab and Count, Stage 2
Launch
Groups of 2
“Now you will choose from other centers we have already learned. One of the choices is to play Five in a Row with a new gameboard. On this gameboard you will add 2 two-digit numbers that make a new ten.”
Display the center choices in the student book.
“Think about what you would like to do first.”
30 seconds: quiet think time
Activity
8 minutes: center work time
“Choose what you would like to do next.”
8 minutes: center work time
Student Facing
Choose a center.
Five in a Row
[IMG]
Get Your Numbers in Order
[IMG]
Grab and Count
[IMG]
Activity Synthesis
“What did the centers you chose help you work on?”


correct_option_index: 1