This Instructional Activity is a part of the Lesson 3, Unit 5, Grade 8. In the last lesson, we looked at several tables of values showing the inputs and outputs of functions. Specifically, the rate of change in the situation being described is constant, and the graph of the equation is a line. That is, if we use 𝑥 to denote an input of the function and y its matching output, then the function is linear if the rule for the function can be described by the equation.