# Lesson 18

Representing Situations with Inequalities

### Lesson Narrative

Prior to this point, students have worked primarily with equations in one and two variables. In this lesson, they shift their attention to inequalities. Here and in the next two lessons, students interpret, write, and find solutions to inequalities in one variable. The activities here are grounded in contexts, and the ideas build on the work students have done in grade 7.

The focus of this lesson is on interpreting and writing inequalities that represent the constraints in various situations. As students consider key quantities in a situation, select variables to represent them, and decide whether multiple inequalities (and which ones) are needed, they engage in aspects of mathematical modeling (MP4).

In future lessons, students will use the insights from this lesson to find and interpret the solutions to inequalities that model situations.

### Learning Goals

Teacher Facing

• Interpret and write inequalities that represent the constraints in a situation.

### Student Facing

• Let’s use inequalities to represent constraints in situations.

### Student Facing

• I can write inequalities that represent the constraints in a situation.

Building On