Windstream
Ojk's Precalculus Study Page: Functions
An introduction to the basic terminology of functions, including how to use the vertical line test on the graph of a relation as a means of testing whether or not it is a function.
University of Cambridge
University of Cambridge: Nrich: What Are You Plotting?
This one page website is for practicing graphing ordered pairs. It lets you know right away if your choice is incorrect. At the bottom of the page their is a challenge with the solution just a click away.