# Lesson 11

Center Day 2 (optional)

## Warm-up: Number Talk: Make 100 (10 minutes)

### Narrative

The purpose of this Number Talk is to elicit strategies and understandings students have for adding more than 2 two-digit numbers by making 100. The unit of cents also encourages students to consider how the value could be expressed using dollars, cents, or a combination of the two units. These understandings help students develop fluency.

### Launch

• Display one expression.
• “Give me a signal when you have an answer and can explain how you got it.”
• 1 minute: quiet think time

### Activity

• Keep expressions and work displayed.
• Repeat with each expression.

### Student Facing

Find the value of each expression mentally.

• $$80¢ + 20¢ + 37¢$$
• $$80¢ + 20¢+ 37¢+ 42¢$$
• $$75¢ + 37¢ + 25¢$$
• $$75¢ + 80¢ + 25¢ + 20¢$$

### Activity Synthesis

• Revisit a student strategy that shows looking for a way to make 100 first and expresses the total in cents.
• “Who can restate _____'s reasoning in a different way?”
• “Who can restate _____'s reasoning using dollars and cents?”

## Activity 1: Introduce How Close?, Add to 1,000 (15 minutes)

### Narrative

The purpose of this activity is for students to learn stage 4 of the How Close center. Students pick a given number of digit cards and then choose a subset of those to make an expression that yields a number as close as possible to the target number. Before playing, students remove the cards that show 10 and set them aside. Each student picks 8 cards and chooses 5 or 6 of them to create 2 three-digit numbers. Each student adds the numbers. The score for the round is the difference between each student's sum and 1,000. Students pick new cards so that they have 8 cards in their hands and then start the next round. The player with the lowest score after 10 rounds wins.

### Required Materials

Materials to Gather

Materials to Copy

• How Close? Stage 4 Recording Sheet

### Launch

• Give each group a set of number cards and two copies of the blackline master.
• “We are going to learn a new way to play the How Close center.”
• “Before you play, remove the cards that show 10 and set them aside.”
• “Each person picks 8 cards and chooses 6 of them to create 2 three-digit numbers. Then add your three-digit numbers.”
• “The score for the round is the difference between your sum and 1,000.”
• “Then pick new cards so that you have 8 cards in your hand and then start the next round.”
• “The player with the lowest score after 10 rounds wins.”
• Answer any questions or play a round with the class as needed.

### Activity

• 10 minutes: partner work time

### Activity Synthesis

• “What strategies did you use to add the numbers?”

## Activity 2: Introduce Five in a Row, Add Within 1,000 with Composing (25 minutes)

### Narrative

The purpose of this activity is for students to learn stage 8 of the Five in a Row: Addition and Subtraction center. Students add within 1,000 with sums that require composing units when adding by place.

Then, students choose from any stage of previously introduced centers.

• Five in a Row
• How Close?

### Required Materials

Materials to Gather

Materials to Copy

• Five in a Row Addition and Subtraction Stage 8 Gameboard

### Required Preparation

• Each group of 2 needs 10 counters and 2 paper clips.
• Gather materials from:
• Five in a Row, Stages 7–8
• How Close, Stage 4

### Launch

• Groups of 2
• Give each group two paper clips, counters, and a gameboard.
• “We are going to learn a new way to play the Five in a Row center. The center is the same as previous versions, but now you might need to compose new units when you add.”
• “Play this new version of Five in a Row with your partner.”

### Activity

• 10 minutes: partner work time
• “Now you can choose another center. You can also continue playing Five in a Row.”
• Display the center choices in the student book.
• Invite students to work at the center of their choice.
• 10 minutes: center work time
• If time, invite students to choose another center.

### Student Facing

Choose a center.

Five a Row: Addition and Subtraction

How Close?

### Activity Synthesis

• “What did you like about the activities you worked on today?”

## Lesson Synthesis

### Lesson Synthesis

“When might you need to add numbers like the ones you worked with in these centers?”