# Activities

• • ##### Subject Area

• Math: Algebra I: Linear Functions

• ##### Author 6-8

45 Minutes

• ##### Device
• TI-73 Explorer™
• TI-Navigator™

## Perpendicular or Parallel?

#### Activity Overview

Students will use TI 73 calculators to explore equations that create parallel and perpendicular lines. Teacher will use the screen capture feature of the Navigator system to display students graphs and equations to discuss observations to realize that equations with equal slopes and different y intercepts create parallel lines and opposite reciprocal slopes create perpendicular lines.

#### Before the Activity

Create an index card for each student with 2 equations on it. Be sure some equations form parallel lines and some form perpendicular lines.

#### During the Activity

1. Students need to be logged onto Navigator 2. Students quit out of the navigator screen, go to the "y=" screen ,enter the 2 equations on their index card and graph. 3.Teacher captures students' graphs using the Screen Capture feature of Navigator. 4. Teacher moves all the graphs of parallel lines to the top of the screen. 5. Students go back to their "y=" screen. 6. Teacher refreshes the capture screen to show the equations that correspond to the parallel lines. Discuss what these equations have in common and help students realize that equal slopes and different y intercepts create parallel lines. 6.Students go back to their graph screens and teacher recaptures them. 7 Move the perpendicualr graphs to the top of the screen and repeat the activity. 8. After observations have been made, ask student to clear their "y=" screens and enter 2 equations of their choice that will create parallel lines, then graph. 9 Teacher captures these graphs to be sure all form parallel lines. Students can then go back to their "y=" screens, refresh capture and look at the equations.

#### After the Activity

My algebra 1 students were really engaged in this activity. It helped them remember the characteristics of equations that form parallel and perpenducular lines.