Lesson 15

The purpose of this warm-up is to elicit the idea that there can be a connection between drawings and expressions, which will be useful when students interpret the numbers and symbols in an expression in relation to drawings. While students may notice and wonder many things about the image and expression, the important discussion points are that there are 3 red counters and the number 3 and that there is 1 yellow counter and the number 1.

• Groups of 2
• Display the image.
• “What do you notice? What do you wonder?”
• 1 minute: quiet think time

• “Discuss your thinking with your partner.”
• 1 minute: partner discussion
• Share and record responses. 

• “How many counters are there? How do you see them?” (4. I see 1 yellow  counter and 3 red counters.)
• “In the next activity, we will match expressions to drawings.”

The purpose of this activity is for students to match drawings to expressions. Students use the structure of the dots to decide whether they represent an addition or subtraction expression and then identify that expression (MP2, MP7).

• Groups of 2
• “Draw a line to match each drawing to an expression. Be prepared to share your thinking.”

• 4 minutes: independent work time
• “Share your matches with your partner.”
• 2 minutes: partner discussion

• Display the 9 circles with 2 crossed out:

  

  

• “For the expression \(9 - 2\), where do you see the 9 in the drawing? Where do you see the 2?” (There are 9 circles and 2 circles are crossed out.)

• Display the 7 red counters:

  

  

• “Which expression did you match to this drawing? Why?” (\(7 + 0\), because 7 and 0 more is still 7.)
• “When we add 0, there are none added, so the drawing shows 7 and 0 more.”

The purpose of this activity is for students to create a drawing when given an expression and to fill in expressions when given a drawing.

• Groups of 2
• Display student book.
• “What do you notice? What do you wonder?” (There are expressions and drawings. Some of the expressions are missing. Some of the drawings are missing. I wonder why one of the drawings has red and yellow.)
• 30 seconds: quiet think time
• 1 minute: partner discussion
• Share and record responses.
• “We noticed that there are some things missing. Work with your partner to fill in the missing expressions and drawings.”

• 5 minutes: partner work time

If students draw an image of addition for a subtraction expression or an image of subtraction for an addition expression, consider asking:

• “What do you know about this expression?”
• “Which part of the expression tells us whether to add or subtract? How can that help you figure out what to draw?”

• Display image from student book:

  

  

• “What expression did you write to go with this drawing?” (\(6 - 3\))
• “Where do you see the 3 circles that are crossed out in the expression?”
• “Where do you see all 6 circles in the expression?”

The purpose of this activity is for students to learn stage 3 of the Shake and Spill center. Students practice counting to find the total of 2 groups of objects and representing addition with an expression.

After they participate in the center, students choose from any stage of previously introduced centers.

• Number Race
• Math Stories

• Each group of 2 needs 10 two-color counters.
• Each group of 2 needs access to a yellow crayon and a red crayon.
• Gather materials from: 
  • Number Race, Stage 1
  • Math Stories, Stages 1 and 2

• Groups of 2
• Give each group of students two-color counters and red and yellow crayons. Give each student a recording sheet.
• “We are going to learn a new way to play Shake and Spill. One partner will choose some counters, shake them, and spill them. Then draw a picture to show the red and yellow counters. Work together to figure out how to fill in an expression to show how many red and yellow counters. Take turns shaking and spilling the counters.”

• 8 minutes: partner work time
• “Now you can choose another center. You can also continue playing Shake and Spill.”
• Display the center choices in the student book.
• Invite students to work at the center of their choice. 
• 10 minutes: center work time
• If time, invite students to choose another center.

• Display \(4 + 3\).
• “Andre and Tyler wrote \(4 + 3\). What do you think their counters looked like?” (4 red counters and 3 yellow counters. 4 yellow counters and 3 red counters.)