Unit 2, Lesson 10
Introducing Graphs of Proportional Relationships
Grade 7
Preparation
Lesson Narrative
This lesson introduces an important way of representing a proportional relationship: its graph. Students plot points on the graph from tables, and, by the end of the lesson, start to see that the graph of a proportional relationship always lies on a line that passes through the origin, . (They will be able to explain why this is true in grade 8.) They match tables and graphs of given situations and articulate their reasons for each match (MP3).
- Compare and contrast (orally) graphs of relationships.
- Generalize (orally and in writing) that a proportional relationship can be represented in the coordinate plane by a line that includes the “origin” or by a collection of points that lie on such a line.
- Justify (orally) that a table and a graph represent the same relationship.
Let’s see how graphs of proportional relationships differ from graphs of other relationships.
Required Preparation
For the digital version of the activity, acquire devices that can run the applet.
For the digital version of the activity, acquire devices that can run the applet.
Prepare copies of the answer key from the Blackline Master and place them in envelopes for students to access to check their work when they finish.
The origin is the point in the coordinate plane. This is where the horizontal axis and the vertical axis cross. The origin is sometimes marked with the symbol .