Lesson 14

• Display the number.
• “What do you know about 10?”
• 1 minute: quiet think time

• Record responses.
• “How could we show the number 10?”

• “Tell your partner 2 different ways that we can make 10.”

The purpose of this activity is for students to learn stage 2 of the What’s Behind My Back center. Students snap a tower of 10 cubes into two parts and hide one part behind their back. Then, their partner determines how many connecting cubes are hidden. Students may use connecting cubes, 10-frames and counters, fingers, or drawings to figure out how many connecting cubes are hidden. As they choose a strategy, they will be making use of appropriate tools strategically (MP5). Monitor for students who:

• create another tower of 10 connecting cubes, snap it into two pieces to show the cubes that are showing and then count the rest of the cubes to determine how many cubes are hidden
• hold up the same number of fingers as the number of connecting cubes that are showing and count the number of fingers that are down to determine how many connecting cubes are hidden
• place counters on a 10-frame to represent the connecting cubes that are showing and count the empty squares to determine how many connecting cubes are hidden

• Each group of 2 need 20 connecting cubes.

• Groups of 2
• Give each group of students 20 connecting cubes. Give each student a recording sheet and access to two-color counters and 10-frames.
• “We are going to learn a new way to play the What's Behind My Back? center.”
• “Work with your partner to make one tower with 10 connecting cubes.”
• 1 minute: partner work time
• “Choose who will go first. Snap the tower into two parts and hide one of the parts behind your back. Show your partner the other part.”
• 30 seconds: partner work time
• “Figure out how many cubes are hidden behind your partner’s back.”
• 2 minutes: independent work time
• “Draw or color the connecting cube tower to show the two parts that the tower snapped into. Work together to fill in an equation to show the total number of connecting cubes in the tower and the two parts that the tower snapped into.”
• 2 minutes: partner work time
• “Take turns snapping the tower of 10 cubes and hiding one part.”

• 8 minutes: partner work time
• Monitor for students who use the methods outlined in the activity narrative.

• Select previously identified students to share.
• “How did making another tower of 10 cubes help you figure out how many cubes were hidden?”
• “How did your fingers help you figure out how many cubes were hidden?”
• “How did putting counters on the 10-frame help you figure out how many cubes were hidden?”

The purpose of this activity is for students to determine how many are needed to make 10 when added to a given number. This activity is presented as the same context as the first activity, except students are not shown the visual of the cubes. Because the context is connecting cubes, one natural way to determine how many cubes are hidden is to create and snap a tower of 10 cubes. Students may also use their fingers or put counters on a 10-frame. As they choose a strategy, they reason abstractly and quantitatively (MP2) and they may choose to use appropriate tools strategically (MP5).

• Groups of 2
• Give students access to connecting cubes, two-color counters, and 10-frames.
• Read and display the task statement.
• “Show your thinking using drawings, numbers, words, or objects.”

• 3 minutes: independent work time
• 2 minutes: partner work time
• Monitor for students who build a tower and snap off 4 cubes to figure out how many cubes are missing.
• “Fill in an equation to show Han’s cubes.”
• 1 minute: partner work time

If students are unsure of how to find the missing part, consider asking:

• “Can you use cubes to show what happened in the story?”
• “How can you use the cubes to help you figure out how many cubes Han was hiding behind his back?”

• Invite students who built towers of connecting cubes to show how they figured out how many cubes were hidden.
• Display a 10-frame with 4 red counters and 6 yellow counters. Display a tower of 10 connecting cubes broken into 4 and 6:

  

  

  

  

• “How is making 10 with connecting cubes the same as using a 10-frame?” (I get the same combinations of numbers to make 10. 4 connecting cubes and 6 connecting cubes make 10 just like with counters.)

The purpose of this activity is for students to choose from activities that offer practice with counting, adding, composing, and decomposing numbers.

Students choose from any stage of previously introduced centers.

• What’s Behind My Back?
• Math Fingers
• Shake and Spill
• Counting Collections
• Roll and Add

• Gather materials from: 
  • What's Behind My Back, Stages 1 and 2
  • Math Fingers, Stages 1-4
  • Shake and Spill, Stages 1-3
  • Counting Collections, Stage 1
  • Roll and Add, Stages 1 and 2

• Give students access to 10-frames,
• “Today we are going to choose from centers we have already learned. You can also continue playing What’s Behind my Back?”
• 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 a tower of 10 cubes, snapped into 9 cubes and 1 cube.

  

  

• “What are the parts that make 10 that Elena found?” (9 and 1)
• “What equation can Elena write?” (\(10 = 9 + 1\))