Graphs of Proportional Relationships - What are the two important characteristics?

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Students will be able to determine if the graph of a relationship is proportional, and thus state the constant of proportionality and equation for the relationship.

Big Idea

Is your graph a straight line? Does it pass through the origin? This lesson helps you determine if graphs are proportional!


10 minutes

OpenerAs students enter the room, they will immediately pick up and begin working on the opener – Instructional Strategy - Process for openers.  This method of working and going over the opener lends itself to allow students to construct viable arguments and critique the reasoning of others, which is mathematical practice 3

Learning Target:  After completion of the opener, I will address the day’s learning targets to the students.  In today’s lesson, the intended target is, “I determine if a graph represents a proportional relationship, and I can determine the constant of proportionality from a graph and the equation for proportional relationships.” Students will jot the learning target down in their agendas (our version of a student planner, there is a place to write the learning target for every day). 

Thoughts from Me! In this lesson, students will be looking for patterns and repeated reasoning, and drawing conclusions (mathematical practices 7 and 8).  Using real world problems, students will create graphs (mathematical practice 4) and given a graph, students will be able to determine an equation and whether or not the relationship is proportional (mathematical practice 2). It will be important that students pay close attention to precision (mathematical practice 6), and use tools (calculator, graph, table) as needed (mathematical practice 5). 


40 minutes

Summary + Homework

10 minutes

Instructional Strategy - Table DiscussionTo summarize this lesson, I will have students have a table discussion on the question:  What are the two characteristics of the graph of a proportional relationship? 

Homework: As students are having their table discussion, I will pass out the night’s assignment.  I have left additional time within this lesson for students to begin on the assignment, as I want to make sure they have a good grasp on it before they get home.