**ENGAGE**

1. As students enter the classroom, they should be given a group indicator that tells them where to sit until dismissed to staircase work location. Inform the students that their mission will be to determine whether a pair of equations of lines are parallel.

**EXPLORE**

2. Student groups should measure the rise and the run of the steps to find the slope of the stairs. They should record these findings on their own paper (this information is to be used to key into their graphing calculators).

3. The students should come back to the classroom and key their information into their graphing calculators (using the list key on the graphing calculator) to determine if the staircases make parallel lines and have parallel slopes. They should look for patterns, develop equations based on data, and list slope conclusions based on data. The groups must agree on findings and be able to justify.

3. If students are unable to identify rise and run values, provide necessary feedback to move them forward with their thinking. Refer to Rise over Run: https://www.youtube.com/watch?v=zTa0xTu9Yv4 (if your school system does not allow YouTube access, you may download the video using http://www.keepvid.com/)

Refer to: https://www.khanacademy.org/math/algebra/linear-equations-and-inequalitie/slope-and-intercepts/v/slope-of-a-line

**EXPLAIN**

4. The teacher should be sure that students are using slope correctly to verify parallel lines.

5. Groups will discuss properties discovered and begin justifying their ideas; along with creating equations and graphs to match their tables in the calculator.

6. Allow students time to prepare attractive posters to share with the class to begin discussions about parallel, along with having the groups share their findings using the Smartview function of the calculator.