Lesson objective: Solve two-step word problems including a variable.

This lesson helps to build procedural skill with solving two-step word problems including a variable. A variable is used here because it supports the representation of the unknown quantitiy. This work develops students' understanding that we can represent unknown quantities in equations using letters.

Students engage in Mathematical Practice 2 (Reason abstractly and quantitatively) as they create logical representations of the problem at hand, including a variable for the unknown quantity.

**Key vocabulary:**

- equation
- unknown quantity
- variable