Lesson 2: Solving by Graphing
Duration of Days: 1
Lesson Objective
Students will estimate solutions to a system of two linear equations by graphing.
Students will understand that the point of intersection (x,y) represents the solution that satisfies both equations simultaneously
How can we use a graph to find a solution that works for two different linear equations?
What does the point where two lines cross tell us about the relationship between those two variables?
Is an intersection point found by graphing always an exact solution?
System of Equations, Point of Intersection, Solution, Ordered Pair, Slope (m), y-intercept (b), and Linear Relationship
8.EE.C.8a: Understand that solutions to a system of two linear equations in two variables correspond to points of intersection of their graphs.
8.EE.C.8b: Estimate solutions by graphing the equations
Purpose: To move from conceptual "investigations" to the formal skill of graphing two lines on a single coordinate plane to find a common solution.
DOK Level: 2 (Skill/Concept)
Students may struggle to accurately identify the y-intercept or slope when equations are not in slope-intercept form.
Students may think any point where the lines are "close" is a solution, rather than the exact intersection point.
Provide coordinate grids with pre-labeled axes for students who struggle with spatial organization.
Use visual activities to gamify the search for intersection points.
Offer sentence starters for students to explain why a point is or is not a solution.
Exit Ticket