Domain and Range

Relations, and functions, and line tests, oh my! An instructional slideshow demonstrates the definitions of a relation, a function, and the domain and range of a relation. Viewers then learn how to use mappings and vertical line tests to determine whether a relation is a function.

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Instructional Ideas

  • Provide more examples of determining domain and range, as well as determining whether a relation is a function
  • Challenge your class to determine whether a relation given by a table of values represents function; such an example is not provided in the lesson
Classroom Considerations

  • While the lesson is titled "Domain and Range," the vast majority of the lesson focuses on determining whether a relation is a function
  • The first slide references the previous lesson (Intersecting Graphs); you can skip this slide without affecting understanding
Pros

  • Provides a link to a Web applet that allows users to drag a vertical line across the graphs of the example functions to test whether a relation is a function
Cons

  • The real-world example of neighbors and cars might not be entirely correct, as it is possible for a neighbor to have more than one car
  • Description of vertical line test does not take into consideration the case where a vertical line does not cross the graph of the relation