# Lesson 13

Number Line Distances

These materials, when encountered before Algebra 1, Unit 4, Lesson 13 support success in that lesson.

### Lesson Narrative

In this lesson students examine distances between numbers on the number line. First, the need for absolute value is motivated by asking students to come up with a way to find the distance between 2 numbers, $$a$$ and $$b$$. Then students find numbers that are a given distance away from a number. In the associated Algebra 1 lesson, students begin the work of thinking about absolute value as a function. Interpreting distances between numbers is essential for the work in the Algebra 1 lesson and supports their thinking about absolute value in upcoming lessons.

Students must look for and make use of structure (MP7) when they write expressions for finding the distance between two numbers on a number line.

### Learning Goals

Teacher Facing

• Find distances on the number line using subtraction.

### Student Facing

• Let’s calculate distances between numbers.