NY Next Generation Math AI-A.REI.12

MathGrades 9–12Represent and solve equations and inequalities graphically.

The Standard

Graph the solutions to a linear inequality in two variables as a half-plane (excluding the boundary in the case of a strict inequality), and graph the solution set to a system of linear inequalities in two variables as the intersection of the corresponding half-planes.

New York State Next Generation Mathematics Learning Standards

Teacher's field guide

What This Standard Means

What Students Need to Do

Students graph a linear inequality in two variables as a half-plane and distinguish solid from dashed boundaries. They find solutions to systems by intersecting the corresponding half-planes.

What Mastery Looks Like

The student graphs each boundary line, shades the correct side, and identifies the overlap for a system. Test points confirm both the shading and whether boundary points belong.

Common Misconceptions

Students may shade the wrong side, use a solid boundary for a strict inequality, or treat a boundary line as the whole solution. They may ignore one inequality when naming the system's solutions.

How to Assess It

Ask students to graph y greater than 2x minus 1 and y less than or equal to 5, then test one boundary and one overlap point.

Lesson moves

Ways to Teach It

  1. Layer transparent half-plane sheets over a coordinate grid to reveal the intersection of two inequalities.

  2. Ask students how the inequality symbol determines whether boundary points count as solutions.

  3. Play shading check by testing coordinate cards against student-drawn half-planes and systems.

  4. Model a production plan with two resource limits and interpret the feasible overlap on a graph.

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