Lesson 4
Center Day 1
Warmup: Number Talk: Use Tens to Add (10 minutes)
Narrative
The purpose of this Number Talk is to elicit strategies and understandings students have for making ten to find sums within 50. When students notice how they can make a ten when finding the value of each expression or when they use one sum to find the value of the next sum, they look for and make use of structure and express regularity in repeated reasoning (MP7, MP8).
Launch
 Display one expression.
 “Give me a signal when you have an answer and can explain how you got it.”
 1 minute: quiet think time
Activity
 Record answers and strategies.
 Keep expressions and work displayed.
 Repeat with each expression.
Student Facing
Find the value of each expression mentally.
 \(9 + 6\)
 \(29 + 6\)
 \(39 + 7\)
 \(39 + 9\)
Student Response
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Activity Synthesis
 “Did anyone have the same method but would explain it differently?”
 “Did anyone approach the problem in a different way?”
Activity 1: Introduce How Close? Add to 100 (20 minutes)
Narrative
The purpose of this activity is for students to learn stage 3 of the How Close center. Each student picks seven cards and chooses four of them to create 2 twodigit numbers. Each student adds the numbers and the student whose sum is closest to 100 wins a point for the round.
Required Materials
Launch
 Groups of 2
 Give each group a set of number cards and recording sheets.
 “We are going to learn a new way to play How Close? Let’s play one round together.”
 Demonstrate removing any card that shows the number 10.
 “First we each take seven cards.”
 Display seven cards for you and seven for the class.
 “Then we each choose four numbers to make 2 twodigit numbers. We want to choose numbers that will have a sum as close to 100 as possible without going over.”
 Demonstrate making twodigit numbers and invite students to share what numbers they would make from the student set of cards.
 “Now we both add our numbers so we can see who has a sum closer to 100.”
 Demonstrate adding and comparing the numbers.
 “The person with the sum closer to 100 gets one point. Then you each choose four more cards so that you have seven cards to start your next round. The person who gets more points wins.”
Activity
 10 minutes: partner work time
Activity Synthesis
 Display seven cards.
 “What numbers would you make to get as close as possible to 100?”
Activity 2: Centers: Choice Time (20 minutes)
Narrative
The purpose of this activity is for students to choose from activities that focus on twodigit numbers.
Students choose from any stage of previously introduced centers.
 Target Numbers
 Five in a Row
 Get Your Numbers in Order
Required Materials
Materials to Gather
Required Preparation
 Gather materials from:
 Target Numbers, Stages 1–3
 Five in a Row, Stages 1–6
 Get Your Numbers in Order, Stage 1
Launch
 Groups of 2
 “Now you will 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.
Target Numbers
Five in a Row
Get Your Numbers in Order
Activity Synthesis
 “What did you practice and get better at in your center?” (I worked on adding numbers by composing a ten.)
Lesson Synthesis
Lesson Synthesis
“How did you and your partner work together during centers? What went well? What can we continue to work on?”