Instruct students to plot two points on a graph by using the x and y coordinates of two sets of ordered pairs provided by you. The first number in a set of coordinates is "x" and the second number is "y." Locate the "x" coordinate on the graph and then move up for a positive "y" coordinate or down for a negative "y" coordinate until the "y" coordinate is located. Place the dot on the graph at this point.
Demonstrate how to place a straight edge on the graph and draw a line from one point to the other point.
Label one set of coordinates as "1" and the other set as "2." Typically, subscript numbers are used to designate each set of coordinates.
Find slope by subtracting the y1 coordinate from the y2 coordinate, and subtract the x1 coordinate from the x2 coordinate. Put the number representing the difference between y coordinates (the rise) over the the number representing the difference between the x coordinates (the run), to create a fraction. This fraction is the slope of the line.
Assign students to measure different sets of steps or stairs in your school. Be sure to include sets of steps that are not identical. Instruct students to use measuring tapes to measure the width of a step (run) and the distance from the top surface of one step to the top surface of another step (rise), and record the data.
Instruct students to graph the slope of each set of steps or stairs measured. Compare the slopes.