# Lesson 18

## Warm-up: How Many Do You See: More Double 10-frames (10 minutes)

### Narrative

The purpose of this How Many Do You See is for students to subitize or use grouping strategies to describe the images they see. This warm-up is similar to the warm-up in the previous lesson. The teacher can notice if the students’ approach to the warm-up is different after the activities in the previous lesson. When students use grouping strategies to visualize the quantities in the $$10 + n$$ structure they come to see that some can be taken from one group and added to the other to make a ten and some more (MP7).

### Launch

• Groups of 2
• “How many do you see? How do you see them?”
• Flash the image.
• 30 seconds: quiet think time

### Activity

• Display the image.
• 1 minute: partner discussion
• Record responses.
• Repeat for each image.

### Student Facing

How many do you see?
How do you see them?

### Student Response

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### Activity Synthesis

• “What do these images have in common?” (You can take some dots from one 10-frame and add them to the other. None of the 10-frames are full.)
• “The first image shows $$9 + 5$$, but if we share one yellow with the top 10-frame we could write $$10 + 4$$.”
• Write $$9 + 5 = 10 + 4$$.
• “What expressions could we write for the second image?” ($$3 + 9 = 2 + 10$$)

## Activity 1: Expression Match (10 minutes)

### Narrative

The purpose of this activity is for students to use what they know about making a ten to identify which addition expressions are equivalent to $$10 + n$$ expressions. Students should have access to double 10-frames and connecting cubes or two-color counters.

The Compare Stage 2 Addition Cards will be used again in a later lesson.

### Required Materials

Materials to Gather

Materials to Copy

• Compare Stage 2 Addition Cards to 20

### Required Preparation

• Create a set of Compare Stage 2 Addition Cards to 20 from the blackline master for each group of 3.

### Launch

• Groups of 3
• Give each group a set of cards and access to double 10-frames and connecting cubes or two-color counters.

### Activity

• 8 minutes: small-group work

### Student Facing

1. Take out all the expression cards that have the number 10.
2. Mix up the rest of the cards.
3. Pick a card.
4. Place the card under the expression with 10 that it is equal to.

### Student Response

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### Activity Synthesis

• “We are going to create a poster and do a Gallery Walk.”

## Activity 2: Compare and Connect: Gallery Walk (15 minutes)

### Narrative

The purpose of this activity is for students to create a poster to show all the expressions equivalent to their assigned $$10 + n$$ expression. Before the activity, assign each group an expression for which they will make a poster. Then, students get into new groups of three and each group visits three posters. Students consider what patterns they notice between the expressions on the poster. Students may notice there is a relationship between the addends of equivalent expressions. For example, when one addend decreases by 1, the other addend in the sum increases by 1 (MP7).

This activity uses MLR7 Compare and Connect. Advances: Representing, Conversing

Action and Expression: Develop Expression and Communication. Provide students with alternatives to writing their observations on paper: students can share their observations verbally, or through drawings.
Supports accessibility for: Language, Conceptual Processing

### Launch

• Groups of 3
• Give each group tools for creating a visual display.
• Assign each group an expression.

### Activity

MLR7 Compare and Connect
• “Create a visual display that shows the expressions equal to the expression with 10 I assigned you.”
• 3 minutes: small group work
• 7 minutes: gallery walk
• During the gallery walk, consider asking:
• “What do you notice about the expressions on the poster?”
• “What patterns do you notice?”
• “Are the patterns the same across all of the posters?”

### Activity Synthesis

• Display posters for $$10 + 1$$, $$10 + 3$$, and $$10 + 5$$.
• “What patterns did you notice as you went from poster to poster?” (I saw that there was an expression with 9 on every poster. For example, $$10 + 3$$ is equivalent to $$9 + 4$$. This is because I can take 1 from the 4 and give it to the 9.) To amplify student language and illustrate connections, follow along and point to the relevant parts of the displays as students speak.
• Record responses as equations (for example, $$10 + 3 = 9 + 4$$).
• Record $$10 + 3 = 9 + 4$$. “Is the same pattern on other posters?” (Yes, it happened on $$10 + 2$$. If I have $$9 + 3$$, I can take one from the 3 and give it to the 9. Then I have $$10 + 1$$.)

## Activity 3: Centers: Choice Time (15 minutes)

### Narrative

The purpose of this activity is for students to choose from activities that offer practice adding and subtracting within 10. Students choose from any stage of previously introduced centers.

• Shake and Spill
• Compare
• Number Puzzles

### Required Materials

Materials to Gather

### Required Preparation

• Gather materials from previous centers:
• Shake and Spill, Stages 3–5
• Compare, Stage 1
• Number Puzzles, Stages 1 and 2

### Launch

• Groups of 2
• “Now you 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.”
• 30 seconds: quiet think time

### Activity

• Invite students to work at the center of their choice.
• 10 minutes: center work time

Choose a center.

Shake and Spill

Compare

Number Puzzles

### Activity Synthesis

• Display nine red counters and cover five yellow counters with a cup.
• “We are playing with 14 counters. How many yellow counters are under the cup? How do you know?”

## Lesson Synthesis

### Lesson Synthesis

Display a double 10-frame with eight counters on the top frame and four on the bottom, and  $$8 + 4 = 10 + 3$$.

“Today we matched addition expressions to equivalent expressions with a 10. Is this equation true or false? How do you know?” (It’s false, because if I move two counters to the top 10-frame then it shows $$10 + 2$$.)

## Cool-down: Unit 3, Section C Checkpoint (0 minutes)

### Cool-Down

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