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

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.

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.
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 3 of the Target Numbers center. Then students choose between that center or others previously introduced.
Students choose from any stage of previously introduced centers.
Target Numbers
Number Puzzles
Mystery Number
Required Materials
Materials to Gather
Connecting cubes in towers of 10 and singles
Materials from previous centers
Number cubes
Materials to Copy
Target Numbers Stage 3 Recording Sheet
Required Preparation
Gather materials form previous centers:
Target Numbers, Stages 1-2
Number Puzzles, Stages 1-4
Mystery Number, Stage 1
Launch
Groups of 2
“Today you will choose from centers we have already learned. One of the choices is to play Target Numbers in a new way. Just like last time, your target number is 95. You will roll two cubes to get your starting number. Then, on each turn, roll three cubes and choose one of the numbers to represent the tens and another number to represent the ones. Add the new number you made to your starting number and record your equation. Continue playing for six rounds to see who gets closest to 95 without going over.”
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.
Target Numbers
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Number Puzzles
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Mystery Number
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Activity Synthesis
“What did you like about the centers you chose?”


correct_option_index: 2