The purpose of this activity is for students to revisit Stage 3 of the Shake and Spill center, introduced in IM Kindergarten. In this stage, students see a quantity broken into two parts in different ways. Earlier in the unit, students used expressions to represent their solution. This time, all students are encouraged to write equations to represent each decomposition. In addition to opportunities to look for the ways student strategies have changed over time, the Activity Synthesis provides an opportunity for students to continue to make sense of the meaning of the equal sign.

During this activity, the teacher collects and displays different equations that students write for the first round. This includes equations where the total is before the equal sign, such as . During the Synthesis, students are encouraged to think about how an equation with the total before the equal sign relates back to the context of playing the game (MP2).

• “What equation did you write for this round?”
• “What is another way you could have written your equation? Does the total always have to go before/after the equal sign?”

• Display collected combinations and equations.
• “What do you notice about the equations I collected during the first round?” (There are different numbers in the equations. They all equal ten. Sometimes the total is before the equation and sometimes it is after.)
• “What does the equation mean?” (The 10 counter total is the same amount as 7 red counters and 3 yellow counters or 7 yellow and 3 red.)
• Highlight student responses to emphasize:
  • The equal sign means “the same amount as” or “equals.”
  • The addition expression or the total could be on either side or the equal sign.

The purpose of this activity is for students to revisit Stage 4 of the Shake and Spill center. Students know the total number of counters and the number of red counters and have to determine the number of yellow counters. Earlier in the unit, students recorded an expression for each round. Now students should complete an equation by adding the equal sign and the total. They may do this before or after the lines given on the recording sheet. Students may also record their equation before finding the unknown using a box to represent the unknown, or they may record the equation after they find the unknown.

During the activity, the teacher collects 4–5 student combinations of 10 to display during the Synthesis. It is important to display some equations with the total before the equal sign. In the Synthesis, students have the opportunity to share strategies they used that are related to using known combinations of 10. They also relate the equations to the Shake and Spill game by boxing the part of the equation that says how many yellow counters are under the cup (MP2).

• “How is this game different from the first game we played?” (In the first game, we knew the total, but the number of yellow and red counters changed each time. We could see all the counters and count them to find how many. In this game, we could only see the red counters and had to figure out the yellow.)
• Display 4–5 equations.
• Invite students to share how they determined the unknown addend.
• Consider asking: "How did you use the equations you wrote in the first game to help you find the unknown addend in this game?"

The purpose of this activity is for students to learn a new center called Number Puzzles. Students build fluency for addition and subtraction within 10. They use number cards to fill in addition and subtraction equations up to 10 on a gameboard. The unknown values are in different places in the equations and each digit (0–9) may only be used once in a puzzle. Puzzles with fewer than 10 spaces will have leftover cards.

• "How did you make sure you were putting each number in the right place?"
• “How do you know your equations are true?”