# Lesson 19

Queuing on the Number Line

These materials, when encountered before Algebra 1, Unit 2, Lesson 19 support success in that lesson.

### Lesson Narrative

The mathematical purpose of this lesson is to remind students of the number line as a tool for representing inequalities, and to support strategies for reasoning about inequalities by testing points. This lesson builds on the work students did in grades 6 and 7 when they began representing solutions to inequalities on the number line. The work in this lesson will prepare students for the associated Algebra 1 lesson when they create solutions to inequalities and check them using substitution.

Students have an opportunity to reason abstractly and quantitatively (MP2) as they test specific values in inequalities, and generalize to represent all solutions on the number line.

### Learning Goals

Teacher Facing

- Interpret the meaning of the graph of an inequality
- Reason about what makes sense as a solution to an inequality

### Student Facing

- Let’s use number line to reason about inequalities