Lesson objective: Use equations as a strategy to fluently add and subtract.

This lesson helps to build fluency with addition and subtraction. Equations are used here because they supports students' comprehension of the word problem. This work develops students' understanding that the strategy we use to add or subtract does not change the total or difference.

Students engage in Mathematical Practice 1 (Make sense of problems and persevere in solving them) as they create equations for the story problem

**Key vocabulary:**

- difference
- equation
- model
- total