# Lesson 6

Center Day 1 (optional)

## Warm-up: Number Talk: Decompose and Subtract (10 minutes)

### Narrative

The purpose of this Number Talk is to elicit strategies and understandings students have for decomposing the subtrahend to create a difference that is known or easier to find. These understandings help students develop fluency and will be helpful later in this lesson when students play center games to practice 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.

• $$65 - 25$$

• $$65 - 27$$

• $$55 - 17$$

• $$46 - 18$$

### Activity Synthesis

• “What strategies did you hear people use that showed thinking about decomposing what you were subtracting to make the difference easier to find?” (I broke the second number into tens and ones. I broke the number into tens and as many ones as I could to take away all the ones. Then I counted back what was left.)

## Activity 1: Introduce Number Line Scoot, Twos, Fives, and Tens (15 minutes)

### Narrative

The purpose of this activity is for students to learn stage 1 of the Number Line Scoot center. In this stage, Twos, Fives, and Tens, Students take turns spinning a spinner and moving their cube that interval on one of the shared number lines. Students may use the number they spin to move that number of length units on one number line or decompose the number and move on multiple number lines. Each time a cube lands exactly on the last tick mark of one of the number lines, the player who moved it keeps the cube and puts a new cube on zero on that number line. The first player to collect 5 cubes wins.

The work of this activity builds a foundation for addition on the number line in upcoming lessons.

### Required Materials

Materials to Gather

Materials to Copy

• Number Line Scoot Stage 1 Gameboard
• Number Line Scoot Stage 1 Spinner
• Number Line Scoot Stage 1 Directions

### Launch

• Groups of 2
• Give each group a spinner, paper clip, centimeter cubes, a gameboard, and the directions.
• Display spinner and gameboard.
• “In this game, you spin the spinner and move cubes along the number lines. If you are the one to move a cube directly on the end of a number line you get to keep that cube. You can split your spin between more than one number line.”
• Answer any questions or demonstrate the game for the class if needed.

### Activity

• 8 minutes: partner work time

### Activity Synthesis

• Display a gameboard with several cubes close to the end of some number lines. Then spin the spinner.
• “This is my gameboard and my next spin. Since I have to land exactly on the end of the number line to collect a cube, what move would you make on the gameboard?”

## Activity 2: Centers: Choice Time (25 minutes)

### Narrative

The purpose of this activity is for students to choose from activities that focus on addition or subtraction.

Students choose from any stage of previously introduced centers.

• Capture Squares
• Number Line Scoot
• Number Puzzles

### Required Materials

Materials to Gather

### Required Preparation

Gather materials from:

• Capture Squares, Stages 3 and 4
• Number Line Scoot, Stage 1
• Number Puzzles, Stage 4

### Launch

• “Now you will choose from centers we have already learned. One of the choices is to continue with Number Line Scoot.”
• 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.
• 10 minutes: center work time
• “Choose what you would like to do next.”
• 10 minutes: center work time

### Student Facing

Choose a center.

Capture Squares

Number Line Scoot

Number Puzzles

### Activity Synthesis

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