Lesson 7

The purpose of this lesson is for students to make sense of, represent, and solve Put Together/Take Apart, Both Addends Unknown story problems. Students write equations and explain how they relate to the story problems.

This work builds on work from kindergarten when students composed and decomposed numbers in more than one way and represented these decompositions with their fingers, connecting cubes, two-color counters, drawings, and expressions. Students revisit Put Together/Take Apart, Both Addends Unknown problems through a game in which they decompose a total into two addends. Students record the decomposition with an equation. In Activity 2, students solve and represent story problems based on the context of the game, and explore the different places the total can be represented in an equation, which deepens understanding of the meaning of the equal sign.

• Each group of 2 needs 10 two-color counters and a cup (at least 8 oz).

What evidence have students given that they understand the meaning of the equal sign? Why is it important for students to understand the meaning of the equal sign before solving Addend Unknown problems in the upcoming lessons?