Functions are special types of relations that assign each input value to exactly one output value. Help students learn how to determine if a relation is a function with this eighth-grade algebra worksheet! In What Is a Function?, learners will study relations in the form of ordered pairs, mappings, and tables to determine if they are functions. For an added challenge, students will then be asked to add to given relations to either make them a function or not a function. This worksheet is a great way to help students prepare for learning about specific types of functions, such as linear functions.