Function Notation & Vertical Line Test

We continued learning about relations and functions today. This time though, Mr. S taught us a new way to know if the relation is a function by something called the vertical line test. Basically, if you draw a line going vertically on the graph of the relation and it crosses two different points, then the relation is not a function. Then he taught us about function notation. Saying that "f(x)" is "y". So everytime I see this: "f(x)" I know its "y". And there's a quiz coming up on Friday. For some wierd reason, I have a really bad feeling about it...