Provides middle school math teachers with classroom activities for introducing functions to their students, a skill necessary for algebra. Defines function and gives real life examples of functions in the world: a roller coaster, selling hot dogs, and a rocket being launched. Explains that functions involve input and output values and generalized rules. Shows a seventh grade teacher introducing functions by using a T-chart activity that involves analyzing patterns and relationships in a series of numbers, and then explaining that pattern in words. Describes two activities, a Function Machine and a Guess My Rule hat game, that can be used to help analyze patterns. Stresses that input values on a T-chart should not be put in sequential order and that students should be given an opportunity to verbalize the rule for the function.