This Demonstration shows the average rate of change for different and values for polynomial functions of degree 2, 3, and 4, an exponential function, and a logistic function.

Choose the polynomial of degree four and . Select from -2.8 to 2.8. Make a table for the intervals in which is negative, zero, or positive.

What is the orientation of the secant line (increasing, decreasing or horizontal) when is negative, zero, or positive?

You found a relationship between the value and the position of the secant line. Is this relationship also correct for the exponential function ?