Are x and y Directly or Inversely Proportional? (Day 1 of 2)

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SWBAT recognize and describe Direct Variation using multiple representations and solve for the Constant of Variation (k).

Big Idea

This lesson introduces students to Direct Variation by comparing the equation y=kx to the now familiar equation y=mx + b.

Warm Up

10 minutes

This Warm Up takes about 10 minutes for students to complete and for me to review with the class. I introduce students to Direct Variation in this Warm Up.  I expect my students to recognize that the relationship in this problems is proportional.  I also want students to recognize that the y-intercept is 0 on the graph of the data.  

I demonstrate my review of the Warm Up with the students in the video below.


Power Point / Frayer Model

35 minutes

After reviewing the Warm Up task, I begin to introduce my students to the difference between a situation involving a Direct Variation and a situation that can be modeled as an Inverse Variation. I provide my students with a Frayer Model to take notes as I present to them using this PowerPoint presentation.

Today, we will focus on Direct Variation. Tomorrow we will discuss Inverse Variation. I choose to use a Frayer Model because I want my students to focus on the appearance of a Direct Variation in different algebraic.  The representations I will discuss are: ordered pairs in a table, an equation, and a graph. The Frayer Model helps students organize their notes for each representation. I want them to be able to refer back to this Graphic Organizer to compare Direct and Inverse Variations (as well as other bivariate relationships). Here is a Sample of a completed Frayer Model. 

Exit Slip

5 minutes

Today's Exit Slip will help me to determine how well my students documented the information conveyed during the lesson. I expect this Exit Slip to take about five minutes for the students to complete. After students turn in their Exit Slips, I will share out the answers and encourage students to add information to their Frayer Models, as needed. Although the Exit Slip is not too challenging, I find that summarizing key points at the end of the lesson helps my students with retention of the content.

Tomorrow we will continue with Inverse Variation.