The purpose of this activity is for students to compose a group of 7 objects and identify the parts and total in the design. In the Activity Synthesis, students share their designs and discuss that while the total number of pattern blocks stays the same, the numbers of each type of pattern block changes. As students share, the teacher records an expression to represent the parts in each design.

• Invite 2–3 students who used different numbers of squares and triangles to share their designs.
• “What parts do you see in _____’s design?” (There is a group of 5 green triangles. There is a group of 2 orange squares.)
• As students share, record each design with an expression. 
• “In the past, we used expressions to show when something was added or taken away. We can also write an expression to show the parts that we see. This design has 7 pattern blocks, 5 green triangles and 2 orange squares. I can write that as .”
• “What is the same about each design? What is different?” (They each have 7 pattern blocks. They each have only squares and triangles. The designs look different. They used different numbers of squares and triangles.)
• If needed, say: “Each design had 7 pattern blocks, but they used different numbers of green triangles and orange squares. There were still 7 pattern blocks.”

The purpose of this activity is for students to see 8 pattern blocks broken into 2 parts in multiple ways. Students represent each pattern block design with an expression. When students write an expression to represent the pattern blocks they reason abstractly and quantitatively (MP2).

• “What are the different ways to make 8 that you found in the designs?” (5 and 3, 4 and 4, 6 and 2)
• Display the first and third designs.
• “What is the same about these designs? What is different?” (They both show 5 and 3. They both have 8 pattern blocks. One used more red trapezoids and one used more green triangles.)

The purpose of this activity is for students to choose from activities that offer practice with addition and subtraction.

Students choose any stage previously introduced stage from these centers:

• Check it Off
• Find the Value of Expressions
• Bingo
• Shake and Spill

• Display 4 red counters and 2 yellow counters.
• “Andre was playing Shake and Spill and this is what his counters looked like. What are the two parts that you see in the counters?” (4 and 2)
• “If Andre shakes and spills 6 counters again, what is a different way that his counters could look?” (3 red and 3 yellow, 5 red and 1 yellow)