The purpose of this activity is to reintroduce students to Put Together/Take Apart, Total Unknown story problems. In this type of problem, there is no action, so students need to recognize that the addends must be joined to make up the total. Students were introduced to this type of story problem in kindergarten and solved within 10 using objects or drawings. Students also solved Put Together, Total Unknown problems in Unit 1 in the context of data.

Students begin the activity by looking at the problem displayed, rather than in their books. The Three Reads routine gives students an opportunity to make sense of the problem before looking for a solution. Because there is no action in a Put Together problem, students identify the important quantities and think about how they might represent them before they solve the problem (MP1). At the end of the Launch, students open their books and work on the problem. Students solve in any way they choose, including using objects, drawings, words, or numbers.

This activity uses MLR6 Three Reads. Advances: reading, listening, representing.

• Invite previously identified students to share in the given sequence.
• After each student shares, ask, “How does this representation match the story problem?”

The purpose of this activity is for students to consider two different equations that represent the same story problem. Put Together/Take Apart, Total Unknown problems help students make sense of the commutative property because the two parts can be combined in different orders. Students contextualize the problem and see that each number represents a specific object’s quantity, no matter which order it is presented, and connect these quantities to written symbols (MP2).

Students do not need to learn or use the formal name of the commutative property, but should be encouraged to describe informally what they notice and explain why they think it works. Students will continue to build their understanding of the commutative and associative properties in future lessons.

• Invite previously identified students to share.
• “How does their work show us that matches this story?”
• “How does their work show us that matches this story?”