The purpose of this activity is for students to play Stage 4 of the Shake and Spill center, which was introduced in an earlier unit. This activity supports students in finding the unknown part of an equation in a later activity.

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. 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, students will complete an equation.

• Display the number 3 and the expression .
• “Han and Mai spilled 3 counters and hid the yellow ones. This is what they wrote on the recording sheet. What is missing from the expression? How do you know?” (1 is missing. 2 and 1 are the parts that go together to make 3. If they can see 2 red counters, then 1 yellow counter is under the cup.)

The purpose of this activity is for students to find the unknown value in addition and subtraction equations. This activity is optional, because determining the unknown value of an equation is not required by the standards. Students may know some of the answers, draw a picture, or use counting forward or backward (MP7).

• Invite previously identified students to share.

The purpose of this activity is for students to choose from activities that offer practice with number and shape concepts. Students choose from five centers introduced in previous units. Students can choose to work at any previously introduced stage of these centers:

• 5-Frames
• Roll and Add
• Bingo
• Geoblocks
• Find the Value of Expressions

• “If you were going to teach another student how to play ________ center, what would you tell them or show them?”