Lesson 21
From One to TwoVariable Inequalities
These materials, when encountered before Algebra 1, Unit 2, Lesson 21 support success in that lesson.
Lesson Narrative
In this lesson, students begin the move from onevariable inequalities to twovariable inequalities. They plot points on a coordinate plane that fit a onevariable inequality to see how that divides the plane. Then, students select points that are on, above, or below a line that represents a given equation. In the associated Algebra 1 lesson, students draw the graph that represents solutions to twovariable inequalities. The work of this lesson supports that learning by providing some additional work that builds on their current understanding of onevariable inequalities and linear equations.
Students look for regularity in repeated reasoning (MP8) when they use the points selected by the class that satisfy a onevariable inequality to determine the region of the plane that represents the solution in two dimensions.
Learning Goals
Teacher Facing
 Draw the solutions to onevariable inequalities on a coordinate plane.
 Write points that are on, above, or below a line represented by a given equation.
Student Facing
 Let’s look at inequalities in two dimensions.
CCSS Standards
Print Formatted Materials
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