Lesson 8

• Groups of 2
• Display the image.
• “What is an estimate that’s too high?” “Too low?” “About right?”
• 1 minute: quiet think time
• Display the image.
• “What is an estimate that’s too high?” “Too low?” “About right?”
• 1 minute: quiet think time

• “Discuss your thinking with your partner.”
• 1 minute: partner discussion
• Record responses.

• “Did anyone change their original ‘about right’ estimate? Why did you change it?”
• “Let’s look at our revised estimates. Why were these estimates more accurate the second time?”

The purpose of this activity is for students to represent numbers within 100 using drawings, words, numbers, expressions, and equations. Students choose their favorite number and represent this number in different ways. In the next activity, students participate in a gallery walk to see their classmates’ representations.

• Give each student a piece of blank paper and access to connecting cubes in towers of 10 and singles.
• “We are going to create a class book. First you will plan out your page. Pick your favorite number between 20 and 100. You will represent your number in as many different ways as you can. You need to include at least three expressions. Let’s make a page together.”
• Display the number 84.
• “What are some ways that I can represent this number?” (I can draw 8 tens and 4 ones, 7 tens and 14 ones, \(80 + 4\), \(10 + 10 + 10 + 10 + 10 +10 + 10 + 10 + 4\), \(70 + 14\))
• 30 seconds: quiet think time
• 1 minute: partner discussion
• Record responses.
• If needed, ask:
  • “How can we represent 84 using only 6 tens?”
  • “What other addition expressions could we write?”

• “Now create your page for our book.”
• 5 minutes: independent work time

If students have difficulty finding more than one expression to represent their number, consider asking:

• “How can you show the number using connecting cubes?”
• “Split the collection into two parts. How many are in this part? How many are in this part? What expression can you write?”

• “Talk to your partner about whether your page is easy to read and understand. You can revise your page based on your partner’s feedback.”

The purpose of this activity is for students to interpret representations of numbers up to 100. Students participate in a gallery walk and find representations that are the same and different than their own. If time permits, students can return to their own work and revise based on what they saw in their classmates’ work. As students look through each others' work, they discuss how the representations are the same and different and can defend different points of view (MP3).

• Display student work from the previous activity for the gallery walk.

• Groups of 2

• “Visit different pages and notice which representations are shown. Which are the same as the representations you used? Which are different?”
• 5 minutes: gallery walk

• “How are the representations of your number the same as your classmates’? How are they different?” (We all wrote expressions. Some students made more drawings than I did. I didn't represent my number with all ones, but someone did that for their number.)
• “If you’d like, you can add to or revise the representations on your page.”

The purpose of this activity is for students to choose from activities that offer practice adding and subtracting within 20 and writing numbers up to 120. Students choose from three previously introduced centers. 

• Compare
• How Close?
• Write Numbers

Gather materials from:

• Compare, Stage 2
• How Close, Stages 1 and 2
• Write Numbers, Stages 1-3

• 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

• “How was your center work helpful today?”