# Applying Similar Triangles to Finding the Slope of a Linear Equation

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## Objective

SWBAT see different connections between similar triangles and the slope of a linear equation through differentiated tasks.

#### Big Idea

Bring your 8th grade year full circle and make connections between many focus standards all in two days!

1 minutes

## Opening the Lesson

2 minutes

This lesson is structured so that three different groups can productively begin the similar triangles application of slope quickly and productively.  Group one is designed for students who still struggle to graph linear equations fluently and need extra assistance is getting started.  Group one then begins to examine the structure of rate of change on the graph to see and understand why some students say slope is a vertical change over a horizontal change.  Group two is a group who graphs linear equations fluently and correctly but need to make the new connection to similar triangles and slope between any two points as viable for finding the unit rate of change.  Group 3 is the advanced group who graph fluently and understand the connection to slope between any two points already.  This group is really focusing on using skills to answer a more open question that leads to observations about the coordinates of a dilation centered on the origin and the distance a point is from the center when dilated.

I open by explaining that each group is completing a similar activity by structured in a different way so that each group learns something different about the connection between similar triangles and finding the slope of a linear equation.  I am explicit that groups will be presenting on day two so they need to focus on making at least two connections between slope and similar triangles so they are ready to present to the class as a group.  It is important to be clear about learning intentions and criteria for success.  Click on the video link below to watch a clip on how to apply this strategy in the classroom.

Clarifying and Sharing Learning Intentions and Criteria for Success

## Working the Cooperative Groups + Homework

50 minutes

As students work through the activity, move about the room assessing formatively and providing feedback that moves student learning forward.  As you notice good work and question students about their observations are sure to tell them which ideas you want them to be ready to present to ensure you get a variety of observations throughout the presentation time.  You want to know what students will say before you send them to the board on day 2.  Throughout the work time, you will utilize a variety of teaching strategies.  Click on the links below to watch short videos on how to apply these strategies in the classroom.

Homework:  I did not assign homework today. Most groups completed the assignment but for any groups that did not, I allowed the first 5-10 minutes of the following class period to finish and organize their presentation among themselves.