In an earlier discussion Ms Coombs had the students find the equation of the line that connected the left points of each step of the rate of change step function.  She also had them find the equation of the line connecting the right end points of each step of the step function.

In this clip, Ms. Coombs reviews the pattern for determining a rate of change function from a given quadratic function.

Ms Coombs continues to discuss the pattern to find the rate of change function for a given quadratic function.