MYP 4 Mathematics Lesson

Linear Inequalities: Solving, Graphing, and the Flip Rule

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9th GradeBTC Style / Thinking ClassroomsCCSS.MATH.CONTENT.7.EE.B.4b, CCSS.MATH.CONTENT.HSA.REI.B.350 min

Learning Objective

Students will solve one- and multi-step linear inequalities, represent solution sets on a number line, and justify why multiplying or dividing by a negative number reverses the inequality symbol.

Lesson Overview

Students progress from interpreting inequality symbols on a number line through solving multi-step linear inequalities, culminating in understanding why multiplying or dividing by a negative reverses the inequality sign. Three guiding questions anchor the lesson: what inequalities represent, how to solve and graph them, and why the flip rule exists.

Materials

Vertical whiteboards or chart paper
Dry-erase markers
Markers in two colors (for number lines)
Random grouping tool
Printed Four-Quadrant consolidation note sheets

Scaffolded Task Progression

1Task 1

Look at each inequality symbol and match it to its meaning. Then place a dot on the number line to show ONE value that makes each statement true.

x > 3

x < - 1

x \geq 5

x \leq 0

For each one: Is there more than one value that works? How many?

2Task 2

Show ALL solutions to each inequality on a number line. Use an open circle for

>

<

, and a closed circle for

\geq

\leq

. Shade the correct direction.

x > 3

x \leq - 1

x \geq 0

Launch question — Level 1 (choose at least one):
a)

x < 7

x \geq - 4

x > 0

x \leq 10

x < - 2

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