Difference Quotient versus The Slope Formula

The difference quotient for a function basically gives the slope of the line connecting two points on its graph.  One point is determined by specifying its x-coordinate (x).  The other point is determined by indicating the directed horizontal distance (h) or (delta x) from the first point.  In this GeoGebra Worksheet, students position a secant line so that it passes through these two specific points.  Then they observe that by evaluating the difference quotient using the values x and h, they obtain the same result for the slope of the secant line as could be obtained by using the slope formula to calculate "rise over run."