Lesson 18

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).

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

• Display the image.
• “Discuss your thinking with your partner.”
• 1 minute: partner discussion
• Record responses.
• Repeat for each image.

• “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?” (\(3 + 9 = 2 + 10\))

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.

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

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

• Read the task statement.
• 8 minutes: small-group work

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

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

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

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?”

• 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 \(10 + 1\).)

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

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

• 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

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

• 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?”