Lesson 4

The purpose of this lesson is for students to recognize that on a number line the numbers increase to the right and decrease to the left.

In previous lessons, students learned how to locate a number on the number line and represent numbers with labeled tick marks and points. They used multiples of 5 and 10 to help them locate numbers up to 100 on a number line.

In this lesson, students recognize that as you move to the right on the number line, numbers increase in value because they are a greater distance from 0. Students also use the relative position of numbers and generalize that a number that is greater than a given number if it is farther to the right on the number line. To demonstrate this understanding, students compare numbers within 100 (a skill from grade 1) and use the number line to explain their comparison (MP7).

In a later lesson, students connect this understanding to movement on the number line, as they learn to represent addition as moving to the right and subtraction as moving to the left.

• Each student will need their number line they made in Lesson 1.
• Each group of 2 needs 3 number cubes and 2 counters.

• Each group of 2 needs 2 number cubes and a dry erase marker.
• Put number line recording sheets into sheet protectors. The recording sheets will be used in upcoming lessons.

How did students explain why a number was greater than or less than another number? What can you do to support students who are not yet articulating their reasoning in terms of a number's location on the number line?