 # 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.

##### 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