Unit 4, Lesson 10
On or Off the Line?
Grade 8
Preparation
Lesson Narrative
In this lesson, students consider pairs of linear equations in familiar contexts, one where there is an equation constraining the possible combinations of two quantities and another where there is an initial value and a rate of change. Students interpret the meaning of points on and off the graphs of the equations. After revisiting the idea that coordinates for points on the graph make the associated equation true, students interpret the intersection point of two lines as a special case in which both equations are true. By examining several points on and off the lines, students make use of repeated reasoning to understand their connection to equations (MP8).
- Determine (in writing) a point that satisfies two relationships simultaneously, using tables or graphs.
- Interpret (orally and in writing) points that lie on one, both, or neither line on a graph of two simultaneous equations in context.
Let’s interpret the meaning of points in a coordinate plane.
Required Materials
Activity 3
Required Preparation
None
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