Learning goals: Teacher Facing Calculate the different rates of change of a piecewise linear function using a graph, and interpret (orally and in writing) the rates of change in context. Create a model of a non-linear function using a piecewise linear function, and describe (orally) the benefits of having more or less segments in the model. Full lesson plan (warm-up, activities, synthesis, cool-down prompt) from 8.5 Functions and Volume, Grade 8.