The purpose of this lesson is for students to solve a Put Together/Take Apart, Both Addends Unknown story problem in the context of putting together pattern blocks (MP2). If students finish early, invite them to find multiple solutions to the story problem.

• Invite students who found different decompositions of 10 to share.
• As students share, record each solution with an equation, such as .
• “Did _____ and _____ both show what happened in the story? How do you know?” (Yes, both have 10 pattern blocks, with some triangles and some squares.)
• “In the next activity, we will find more ways that we can make shapes with 10 pattern blocks.”

The purpose of this activity is for students to compose and decompose 10 in multiple ways, in the context of putting together pattern blocks. In order to draw the shapes they created, with pattern blocks, students may draw or trace each shape. Using different colored crayons (red for the red trapezoids, blue for the blue rhombuses) may help students differentiate between the shapes. Students are not expected to draw precise or accurate shapes. Students then fill in the addition expressions to record each way. Students may use a combination of words, numbers, and colors to label how many of each pattern block they used. In the Activity Synthesis, students look for patterns in equations and try to determine if all decompositions of 10 have been found (MP7).

• Display the chart paper labeled “rhombuses” and “trapezoids.”
• “Pick your favorite page in your book. How many blue rhombus pattern blocks and how many red trapezoid pattern blocks did you use to create the shape on your favorite page?”
• Share and record all student responses as equations on a chart. Record the responses systematically:
• If a student shares a decomposition that was previously shared, point to the decomposition that was already listed.
• “What do you notice?” (The numbers in one column go up. The other numbers go down.)
• If not all decompositions of 10 are listed, ask, “Are there any ways to make 10 that are missing from our list? What makes you think that?” (We didn’t write an equation with 4 trapezoids. If we did 6 trapezoids and 4 rhombuses, maybe we could do 4 trapezoids and 6 rhombuses instead.)

The purpose of this activity is for students to learn Stage 4 of the Shake and Spill center. Students use 3, 4, or 5 counters. One student closes their eyes while their partner shakes and spills the counters, and then covers the yellow counters with the cup. The student opens their eyes, determines how many counters are under the cup, and explains how they know. Both students fill in expressions to represent each decomposition. Although determining the unknown part of a total is not required by the standards, this activity helps students build fluency with addition and subtraction within 5. In a future variation of this center, students will play with up to 10 counters.

The recording sheet asks for an expression or an equation. Kindergarten students should fill in the expression. When the same stage is done in grade 1, they will complete an equation.

• Display .
• “Mai was playing Shake and Spill—Cover. She wrote this expression. What could her counters look like?” (1 yellow and 3 red, or 3 red and 1 yellow.)
• If needed, ask, “How many counters are under the cup? How many counters are out on the table?”