In previous lessons, students solved Compare problems where the difference was within 3. They used strategies that made sense to them and interpreted Compare, Difference Unknown problems as unknown addend problems. In this lesson, students continue to make sense of Compare, Difference Unknown problems and different strategies that can be used to solve them. Connecting cubes are used as a context and a tool that can easily elicit and demonstrate strategies based on addition or subtraction. The more concrete representations are also helpful as students work with differences that are larger than 3. As students explain and compare different ways to determine the value of a difference, they deepen their understanding of the relationship between addition and subtraction. They also begin to better understand subtraction as an unknown addend problem.

What did you say, do, or ask during the Lesson Synthesis that helped students be clear on the learning of the day?