Varsity Tutors
Varsity Tutors: Hotmath: Practice Problems: Graphing Functions and Relations
Thirteen problems present a variety of practice graphing functions and relations. They are given with each step to the solution cleverly revealed one at a time. You can work each step of the problem then click the "View Solution" button...
Oswego City School District
Regents Exam Prep Center: Determining Relations and Functions
This resource offers definitions for "relation", "function", and "functional relation", and examples to illustrate each.
Oswego City School District
Regents Exam Prep Center: Definition of a Relation and a Function
Very basic definitions of mathematical relations and functions can be found here. The single example provided shows a relation which is not a function and explains what makes it so.