The purpose of this activity is for students to revisit Stage 3 of the Shake and Spill center, which was introduced in IM Kindergarten. In this stage, students see a quantity broken into two parts in different ways. Students write expressions to represent each decomposition. This activity helps build common experiences for making sense of Put Together/Take Apart, Addend Unknown problems in the next lesson and serves to continue student conversations about the commutative property and other relationships between addends in expressions that have the same value.

During this activity, the teacher collects and displays different expressions that students write for the first round. When displaying student expressions, consider doing so in a way that encourages them to notice the commutative property (for example, recording and next to each other). Although students may write equations, all students are not expected to do so. Students will have opportunities to practice writing equations to represent Shake and Spill and Put Together/Take Apart, Both Addends Unknown problems in Section D.

• Display collected combinations and expressions.
• “What do you notice about the expressions I collected during the first round?” (There are different numbers in the expressions. They all equal 9. Some of the numbers are the same, but in different orders. Sometimes the numbers are the same, but they were for different colors.)
• Display the equation .
• “What does the equation mean?” (The 9 counter total is the same amount as 7 red counters and 2 yellow counters or 7 yellow and 2 red.)
• Display the equation .
• “What does this equation mean?” (The 9 counter total is the same as 2 red counters and 7 yellow counters or 2 yellow counters and 7 red counters.)
• “What is the same about these equations? What is different?” (They have the same total. Everything is the same except the order of the 7 and the 2.)

The purpose of this activity is for students to solve Put Together/Take Apart, Both Addends Unknown story problems in the context of the Shake and Spill center. Students generate different combinations of red and yellow counters and compare different expressions that represent these combinations.

Look for the different ways students generate different combinations, including the way they use their emerging understanding of the commutative property or known facts. For example, students may notice that if they know 9 and 1 is a possible combination, they also know 1 and 9 is a possible combination. When students share this thinking, invite them to use the counters to make their reasoning visible to all students.

• Invite 1–2 students to share the expressions that represent the image of Tyler’s counters.
• Invite 2–3 previously selected students to share some of their combinations and how they generated them.
• “What are other combinations of red and yellow counters Tyler might spill?”
• Annotate student responses with expressions.
• “How are these expressions the same? How are they different?”