Lesson plan

3. Solve systems and graph intersections (C)

teaches Common Core State Standards CCSS.Math.Content.8.EE.C.8a http://corestandards.org/Math/Content/8/EE/C/8/a
teaches Common Core State Standards CCSS.Math.Content.8.EE.C.8b http://corestandards.org/Math/Content/8/EE/C/8/b
teaches Common Core State Standards CCSS.Math.Practice.MP1 http://corestandards.org/Math/Practice/MP1
Quick assign

You have saved this lesson plan!

Here's where you can access your saved items.

Content placeholder

or to view additional materials

You'll gain access to interventions, extensions, task implementation guides, and more for this lesson plan.

Lesson objective: Understand that a point of intersection between two lines on a graph represents a solution to a system of the two equations.

Students bring prior knowledge of graphing functions and linear equations from 8.F.A.1 and 8.F.B.4. This prior knowledge is extended to representing a system of equations on a graph as students connect parallel lines, coinciding lines, or points of intersection to solutions of a system. A conceptual challenge students may encounter is thinking that if two non-parallel lines do not meet in a graphing window, then the system does not have a solution. 

The concept is developed through work with graphs, which visually represents all solutions to linear equations as a line.

This work helps students deepen their understanding of equivalence because a point of intersection shows where two equations are true at the same time.

Students engage in Mathematical Practice 1 (make sense of problems and persevere in solving them) as they make sense of a point of intersection as an ordered pair that makes both equations true in a system of equations.

Key vocabulary:

  • intersection
  • parallel

Special materials needed:

  • graph paper and/or graphing technology