This worksheet gives students focused practice identifying functions across multiple representations, including equations, tables, graphs, and mapping diagrams. Students begin by reinforcing core vocabulary such as independent and dependent variables, inputs and outputs, and then apply the defining rule of a function: each input must produce exactly one output. The problems emphasize careful reading and interpretation rather than pattern-matching.

As the worksheet progresses, students analyze diagrams and graphs using functional reasoning, distinguish functions from non-functions, and justify their conclusions in both multiple-choice and open-response formats. This makes the resource especially effective for building conceptual understanding early in a functions unit or for reinforcing precision before moving into function operations and modeling. A complete answer key supports quick grading and student self-checking.

Keywords: identifying functions, functions vs non-functions, independent and dependent variables, inputs and outputs, vertical line test, Algebra I functions, interpreting graphs, mapping diagrams