Learning goals: Teacher Facing Given a graph of a function, estimate or calculate the average rate of change over a specified interval. Recognize that the slope of a line joining two points on a graph of a function is the average rate of change. Understand that the average rate of change describes how fast the output of a function changes relative to the input over the interval. Full lesson plan (warm-up, activities, synthesis, cool-down prompt) from Alg1.4 Functions, Algebra 1.