Lesson 6

The purpose of this Number Talk is to elicit strategies and understandings students have for strategies for adding based on place value. These understandings help students develop fluency and will be helpful later in this lesson when students will need to be able to add 2 two-digit numbers within 50, and throughout the year as students develop fluency adding within 100.

• 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 strategy.
• Keep expressions and work displayed.
• Repeat with each expression.

• “We have seen lots of different ways to find the sum of 2 two-digit numbers. There will be more opportunities to try out different methods as we work in centers today.”

The purpose of this activity is for students to revist stage 2 of the Number Puzzles center which was first introduced in grade 1. Students work together to use digit cards to make addition and subtraction equations within 20 true. Each digit card may only be used one time on a page.

• Create one set of digit cards from the blackline master for each group of 2.

• Groups of 2
• Give each group a set of digit cards and game boards.
• “We are going to play a game you may have played in first grade called Number Puzzles."
• "In this game, you use digit cards to make each equation true. You can only use each digit card once on the game board.”

• 10 minutes: center work time

• Display Puzzle 1.
• “Which equation would you start with? Why would you start there?”

The purpose of this activity is for students to again choose from activities that focus on adding or subtracting.

Students choose from any stage of previously introduced centers.

• What's Behind My Back?
• How Close?
• Number Puzzles

Gather Materials from:

• What's Behind My Back, Stages 2 and 3
• How Close, Stages 1–3
• Number Puzzles, Stages 1 and 2

• “Now you can choose a different center.”
• Display the center choices in the student book.
• “Think about which center you would like to work on now.”
• 30 seconds: quiet think time

• Invite students to work at the center of their choice.
• 10 minutes: center work time
• "Choose what you would like to do next."
• 10 minutes: center work time

• “What is one thing you learned or got better at by working on the activity you chose?”