Total Duration: 
Greater than 120 Minutes 
Materials and Resources: 
Poster Paper or Poster with grid lines, sticky notes of different types, straight edge, markers, rectangle/square tiles or rectangular/square objects, student may use their own devices or teacher issued graphing calculators. 
Technology Resources Needed: 
Computer with Internet access, LCD Projector and Document camera to share student work (helpful but not necessary.) Smartview with calculator is needed. 
Background/Preparation: 
Teacher:
Students:

ENGAGE As students enter the classroom, they should receive a group that tells where to sit with all needed materials available. Students should be informed that their mission today is to determine whether a pair of equations of lines is perpendicular. EXPLORE 1. Student groups should trace the rectangular/square tile/object on a coordinate plane. Each group can decide to use a L shape from the graph to receive coordinate pairs to input into graphing calculator to generate equations of lines and graphs. Each group can also decide to use a triangle from the traced shape, use distance formula to calculate length values and then verify values as a Pythagorean triple. 2. The students should key their information into their graphing calculators (using the list key on the graphing calculator) to determine if the L shape of the traced object makes perpendicular lines and have perpendicular 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 do not understand perpendicular lines and slopes, provide necessary feedback to move them forward with their thinking. Refer to : http://www.youtube.com/watch?v=VVvErpLG2EQ (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/twovarlinearequations/slope/v/slopeofaline. EXPLAIN 1. The teacher should be sure that students are using slope/distance or pythagorean theorem correctly to verify perpendicular lines. 2. Groups will discuss properties discovered and begin justifying their ideas; along with creating equations and graphs to match their tables in the calculator. 3. Allow students time to prepare attractive posters to share with class to begin discussions about perpendicular, along with having the groups share their findings using the Smartview function of the calculator.

Attachments: **Some files will display in a new window. Others will prompt you to download. 
Assessment Strategies 
EVALUATE Use the rubric provided to assess student work individually and as a group. Students should justify all reasoning stated on poster. The Assessment Process is ongoing. The teacher should visit each group and ask questions to make sure students apply the properties of perpendicular line definitions. Post the posters in the classroom and have students present conclusions. As students present posters and graphing calculator finds, they should compare posters for other information not listed on their group's poster. 
Acceleration: 
Extensions can be to include formal proofs in geometry or have students justify the properties of perpendicular lines using more coordinate and two column proofs. Groups can be random or you can select groups to allow struggling students to find slopes using formulas or inputing information into calculator for graphs. 
Intervention: 
For extra practice or for students who were absent, have them visit: https://www.khanacademy.org/math/ccfourthgrademath/cc4thgeometrytopic/cc4thclassifyingshapes/v/classifyingshapesexamples

View the Special Education resources for
instructional guidance in providing modifications and adaptations
for students with significant cognitive disabilities who qualify for the Alabama Alternate Assessment.
