Education Technology

Middle Grades Math: Definition of Functions

by Texas Instruments


  • Students will determine the domain and range of relationships given as a set of ordered pairs.
  • Students will determine whether or not a relationship is a function or not using the definition.
  • Students will verify that relationships are functions or not by examining the relationship graphically and in a table.


  • relationship
  • input
  • output
  • domain
  • range
  • function

About the Lesson

This lesson involves examining relationships and functions and their inputs, outputs, domains, and ranges.
As a result, students will:

  • Examine a relationship, determine its domain and range, and plot it on a coordinate grid.
  • Examine a relationship in table form with arrows to connect inputs with their given outputs.
  • Learn that a function is a rule that assigns to each input exactly one output and that the graph of a function is the set of ordered pairs consisting of an input and the corresponding output.
  • Students will create their own relationships, one that is a function and one that is not.