This Instructional Activity is a part of the Lesson 3, Unit 5, Grade 8. Example 1 In the last lesson, we looked at several tables of values showing the inputs and outputs of functions. For instance, one table showed the costs of purchasing different numbers of bags of candy. What do you think a linear function is? A linear function is likely a function with a rule described by a linear equation. Specifically, the rate of change in the situation being described is constant, and the graph of the equation is a line.