ALEX Lesson Plans Subject: Mathematics (9 - 12) Title: PER - PIN - TIC - YOU - LER! (Part 2 to Take the Stairs Lesson) Description: This lesson allows students to investigate the slope criteria and characteristics of perpendicular lines using graphing calculators and rectangle/square tiles.  Students will also use equations and graphs.  Students will work cooperatively to develop and justify ideas/conjectures. This is a College- and Career-Ready Standards showcase lesson plan.Subject: Mathematics (9 - 12) Title: Take the Stairs to Slope! Description: This lesson allows students to investigate the slope criteria and characteristics of parallel lines using graphing calculators and school staircases.  Students will also use equations and graphs.  Students will work cooperatively to develop and justify ideas/conjectures. This is a College- and Career-Ready Standards showcase lesson plan.Subject: Mathematics (9 - 12) Title: What do we have in Common?  Discover the properties of the diagonals of quadrilaterals. Description: This inquiry lesson explores the definitions of quadrilaterals and the properties of the diagonals of quadrilaterals to classify quadrilaterals. Students will work cooperatively to justify conclusions. This lesson plan was created by exemplary Alabama Math Teachers through the AMSTI project.Subject: Mathematics (8 - 12) Title: What is the slope of the stairs in front of the school? Description: The purpose of this lesson is to help students apply the mathematical definition of slope to a concrete example. The students will learn to make the appropriate measurements and apply the formula to calculate the slope of the stairs experimentally. Thinkfinity Lesson Plans