Algebra I: Multiplying Inequalities by Negative Numbers

Objectives

• Students will relate the inequality symbol to the location of points on a number line.
• Students will recognize, moreover, that the value of a number depends on its position on the number line and that numbers farther to the left are smaller.
• Students will recognize what operations on an inequality reverse the direction of the inequality.

Vocabulary

• inequality statement

About the Lesson

In this lesson students investigate the effect of multiplying the numbers on a number line by a negative number and the symbolic and graphical representations of the solutions of an inequality. Students will change the value of a multiplier (k) and observe the effects on the position of the resulting number on the number line and in the inequality statements. As a result, students will recognize what operations on an inequality reverse the direction of the inequality.