The purpose of this activity is for students to solve Put Together, Total Unknown story problems through a context they are familiar with—the center game Shake and Spill. To launch the lesson, the teacher plays a round of the game with students and reminds them to draw a box around the number in the equation that answers the question.

As students find sums, they relate addition to counting on. They may also apply what they know about the commutative property. Some of the story problems have the smaller addend first to encourage students to consider using this property (MP7). Students should make sure that the answer to each question is clear in their representations.

In the Activity Synthesis, use two-color counters as well as students’ representations to compare the two counting on methods.

• Invite previously identified students to share in the sequence shown in the list.
• “¿En qué se parecen estos métodos? ¿En qué son diferentes?” // “How are these methods alike? How are they different?” (They all add 3 and 6 and get 9. They all use counting to get the answer. The amounts counted are different. The first one counted all of the counters, the second counted 6 counters, and the third counted 3 counters.)

If students only refer to the solution of 9, consider asking:

• “¿Cómo saben que los dos métodos son correctos?” // “How do you know that both methods are correct?”
• “¿Cómo podemos usar las mismas 9 fichas para pasar del primer método al segundo método?” // “How can we use the same 9 counters to move from the first method to the second?”

• Invite 2–3 groups to share their thinking.
• “Kiran y Clare empezaron con números diferentes, pero obtuvieron el mismo valor. Con tal de que tengamos los mismos 2 números, podemos sumarlos en cualquier orden. // “Kiran and Clare started with different numbers, but they both got the same value. As long as we add the same 2 numbers, we can add them in either order.”
• “¿Cuál método les gusta más? ¿Por qué?” // “Which method do you like best? Why?” (I like adding up from the larger number since it’s faster than adding up from the smaller number.)

The purpose of this activity is for students to find the value of sums within 10. Students may apply what they learned about the commutative property and counting on. They may count on for certain equations, such as or since they can keep track easily, but count all for others. In the Lesson Synthesis, students return to the addition expression cards they used in a previous lesson.

• Invite previously selected students to share.