Lesson 16

• Display one expression.
• “Give me a signal when you have an answer and can explain how you got it.”
• 1 minute: quiet think time

• Record answers and strategies.
• Keep expressions and work displayed.
• Repeat with each expression.

• “Why do the last three expressions all have the same value?” (They are all adding \(65 + 20 + 1\) in different ways.)

The purpose of this activity is for students to learn stage 3 of the Counting Collections center. Students are given a collection of up to 120 objects. They record an estimate for how many objects they think are in their collection. Then, they work with a partner to figure out how many objects are in their collection. Each partner records how many. Students may draw pictures, write numbers or equations, or use base-ten representations to represent their collection.

• Create a collection of up to 120 objects per group of 2 students (buttons, two-color counters, linking cubes, paper clips, pattern blocks, square tiles).

• Groups of 2
• Give each group two recording sheets, a collection of objects, and access to tools to help organize their count.
• “We are going to do more Counting Collections.”
• “This time, you will estimate how many objects are in your collection before you count them. Record your estimate, then count the collection. Record your count.”

• 15 minutes: partner work time time

• “How did you organize the objects in your collection as you counted?”

The purpose of this activity is for students to practice measuring lengths and writing numbers up to 120.

Students choose from any stage of previously introduced centers.

• Write Numbers
• Estimate and Measure

• Gather materials from:
  • Write Numbers, Stages 1–3
  • Estimate and Measure, Stage 1

• Groups of 2
• “Now you are going to work on 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

• 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

• Display numbers 108, 109, 110, 111, 112.
• “What do you notice about these numbers?” (They all have 100. Some have a zero and some don’t. The numbers go in order 8, 9, 10, 11, 12.)