Lesson 10
Center Day 2 (optional)
Warmup: Notice and Wonder: Compare the Representations (10 minutes)
Narrative
Launch
 Groups of 2
 Display the image.
 “What do you notice? What do you wonder?”
 1 minute: quiet think time
Activity
 “Discuss your thinking with your partner.”
 1 minute: partner discussion
 Share and record responses.
Student Facing
What do you notice? What do you wonder?


\(66  28 \)
\(66 = 50 + 16 \)
\(16  8 = 8 \)
\(50  20 = 30\)
\(30 + 8 = 38\)
\(66  28 = 38\)
Student Response
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Activity Synthesis
 “Both of these representations show ways to find the value of \(66  28\). How are they the same? How are they different?” (Both show taking tens from tens and ones from ones. Both show decomposing a ten. One uses baseten diagrams and one uses only numbers and equations.)
Activity 1: Introduce Target Numbers, Subtract Twodigit Numbers (20 minutes)
Narrative
The purpose of this activity is for students to learn stage 5 of the Target Numbers center. Students subtract twodigit numbers to get as close to 0 as possible. For the introduction of this stage, invite students to count by 10 to 100 and represent their count with baseten blocks. Then, they take turns rolling the 3 cubes to get a number to subtract. They choose one of the numbers on the cubes to represent the tens and a different number to represent the ones. Students subtract their tens and ones from the starting number. The difference becomes the first number in the next equation. The player who gets closest to 0 in 6 rounds, without going below 0, is the winner.
Required Materials
Materials to Gather
Materials to Copy
 Target Numbers Stage 5 Recording Sheet
Required Preparation

Each group of 2 students will need 3 number cubes.

Each group of 2 students will need baseten blocks to represent at least 20 tens and 18 ones.
Launch
 Groups of 2
 Give each student a copy of the recording sheet.
 Give each group 3 number cubes and access to baseten blocks.
 “We are going to learn a new way to play Target Numbers. You and your partner will start with 100 and race to see who can reach a number less than 10 first.”
 “Instead of using cards to decide whether to take away tens or ones, you will use number cubes to create a twodigit number and then subtract that number.”
 “First, represent 100 with baseten blocks."
 As needed, invite students to count by 10 to 100 using the baseten blocks or invite student to share how they might represent 100 with the blocks.
 "When it’s your turn, roll all 3 number cubes. Pick 1 number to represent the tens and one number to represent the ones. Then show the subtraction with your blocks and write an equation on your recording sheet.”
 “Take turns rolling and subtracting until the first person reaches a number less than 10.”
 As needed, demonstrate a round with a student volunteer.
Activity
 10–15 minutes: partner work
Activity Synthesis
 Display equation: \(73  \underline{\hspace{1 cm}} = \underline{\hspace{1 cm}}\)
 Draw or display number cubes showing 4, 2, and 5.
 “What twodigit numbers could you create with this roll that would make you need to decompose a ten to subtract? How do you know?” (Sample response: 24 because if you subtract by place, there are only 3 ones, so you would need to decompose to take away 4 ones.)
 “What twodigit numbers could you create that wouldn’t require decomposing a ten? How do you know?” (Sample response: 52 because if you subtract by place there are 3 ones and you can take away 2 ones from 3 ones.)
 “What number would you create to try to get below 10 the fastest? Explain. (54 because it’s the number that lets you take away the most tens and ones.)
Activity 2: Centers: Choice Time (20 minutes)
Narrative
The purpose of this activity is for students to choose an activity to work on that focuses on addition and subtraction within 100 or building fluency with addition and subtraction within 20. Students choose from any stage of previously introduced centers. Stage 4 of Capture Squares is also included as an extension.
 Target Numbers
 Capture Squares
 Five in a Row
Required Materials
Materials to Gather
Required Preparation
Gather materials from:

Target Numbers, Stages 4 and 5

Capture Squares, Stage 3 and 4

Five in a Row, Stage 6
Launch
 “Now you will choose from centers we have already learned. One of the choices is to continue Target Numbers, Subtract Twodigit Numbers.”
 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.
 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
Capture Squares
Five in a Row
Activity Synthesis
 “Which activity did you choose? What did you like about the activity you chose?”
Lesson Synthesis
Lesson Synthesis
“Today we chose activities to work on and worked with a partner during center time.”
Math Community
“Was there something you struggled with today? How did you solve it? Did anyone help you?”