# Lesson 10

Complete Equations

## Warm-up: What do you know about 15? (10 minutes)

### Narrative

The purpose of this What Do You Know About _____? is to invite students to share what they know and how they can represent the number 15.

### Launch

• Display the number.
• “What do you know about 15?”
• 1 minute: quiet think time

### Activity

• Record responses.

### Student Facing

What do you know about 15?

### Activity Synthesis

• “We have shown numbers 11–19 in lots of different ways. We have used fingers, 10-frames, written numbers, and expressions. In the next activity we will show these numbers as equations.”

## Activity 1: What Is Missing? (10 minutes)

### Narrative

The purpose of this activity is for students to fill in equations to represent decompositions of numbers 11–19 on 10-frames. Students fill in either the total or the two parts missing from the equations. When students relate the parts of the 10-frame representations and the equations they reason abstractly and quantitatively (MP2).

MLR8 Discussion Supports. Invite each partner to read the completed equation aloud. Listen for and clarify any questions about the equations.

### Launch

• Groups of 2
• “Use the dots to find the numbers that make each equation true.”

### Activity

• 2 minutes: independent work time
• 3 minutes: partner work time

### Student Facing

$$10 + 8 = \underline{\hspace{1.4 cm}}$$

$$10 + 3 = \underline{\hspace{1.4 cm}}$$

$$10 + 4 = \underline{\hspace{1.4 cm}}$$

$$\underline{\hspace{1.4 cm}} + \underline{\hspace{1.4 cm}} = 16$$

$$\underline{\hspace{1.4 cm}} + \underline{\hspace{1.4 cm}} = 19$$

$$\underline{\hspace{1.4 cm}} + \underline{\hspace{1.4 cm}} = 12$$

### Activity Synthesis

• Display the image with 18 dots and the matching equation.
• “How did you figure out what was missing?” (I counted the dots to find out how many there are altogether.)
• Display the image with 16 dots and the matching equation.
• “How did you figure out what was missing?” (I looked for the two parts. There are 10 on the 10-frame and then there are 6 more.)
• “Sometimes the total number of dots was missing. Sometimes the two parts were missing.”

## Activity 2: Make the Equations True (10 minutes)

### Narrative

The purpose of this activity is for students to complete equations to represent numbers 11–19. Students may know that 17 is 10 and 7 because of repeated practice in this unit. Students may need to use objects or drawings to represent each number and then fill in an equation. While there are many possible equations to represent each number, students have only composed and decomposed numbers 11–19 as ten ones and some more ones throughout this unit, which makes 10 + _____ the most likely way for students to fill in the equations (MP8).

Action and Expression: Internalize Executive Functions. Invite students to plan a strategy, including the tools they will use, for filling in the missing numbers. If time allows, invite students to share their plan with a partner before they begin.
Supports accessibility for: Organization, Conceptual Processing

### Required Materials

Materials to Gather

### Launch

• Groups of 2
• “Find the numbers that make each equation true. You can use objects, drawings, or 10-frames to help you.”

### Activity

• 3 minutes: independent work time
• 3 minutes: partner work time

### Student Facing

1. $$10 + 5 = \underline{\hspace{1.4 cm}}$$

2. $$\underline{\hspace{1.4 cm}} + \underline{\hspace{1.4 cm}} = 16$$

3. $$\underline{\hspace{1.4 cm}} + \underline{\hspace{1.4 cm}} = 19$$

4. $$\underline{\hspace{1.4 cm}} + \underline{\hspace{1.4 cm}} = 13$$

5. $$\underline{\hspace{1.4 cm}} + \underline{\hspace{1.4 cm}} = 17$$

6. $$10 + 1 = \underline{\hspace{1.4 cm}}$$

### Activity Synthesis

• Invite a student who represented 17 on a 10-frame to share.
• “How do the counters and the 10-frame help you fill in the equation?”
• “Where do you see 10 on the 10-frame? Where do you see 7 on the 10-frame?”

## Activity 3: Centers: Choice Time (20 minutes)

### Narrative

The purpose of this activity is for students to choose from activities that offer practice with addition and subtraction, writing numbers, and counting objects.

Students choose from any stage of previously introduced centers.

• Make or Break Apart Numbers
• Bingo
• Number Race
• Grab and Count
• Tower Build

### Required Materials

Materials to Gather

### Required Preparation

• Gather materials from:
• Make or Break Apart Numbers, Stages 1 and 2
• Bingo, Stages 1-4
• Number Race, Stages 1 and 2
• Grab and Count, Stage 1
• Tower Build, Stages 1 and 2

### Launch

• “Today we are going to choose from centers we have already learned.”
• 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.

Bingo

Number Race

Grab and Count

Make or Break Apart Numbers

Tower Build

### Activity Synthesis

• “What center do you hope you can keep playing in upcoming lessons? What do you like about that center?”

## Lesson Synthesis

### Lesson Synthesis

Display $$10 + 9 = 19$$.

“Find a way to show that $$10 + 9$$ is 19.” (Two students show 19 with 10 fingers and 9 fingers. Students use a full 10-frame and 9 counters.)

## Student Section Summary

### Student Facing

We saw and made numbers 11–19 with fingers and 10-frames.

$$10 + 4$$ is 14.
$$10 + 4 = 14$$