Present the idea of a function
Introduce function notation
Explain the relationship between y and f(x)
The lesson features a slide show presentation with cartoons. It explains the concept of mathematical functions and function notation using a vending machine analogy.
If we have a graph of an equation in two variables, we can tell whether or not the graph depicts a function using the vertical line test.
Recall that if y is a function of x, then no two y values can correspond to a single x value. Graphically, this means that no vertical line can intersect the graph at more than one point. If a vertical line can be found that intersects the graph more than once, then the graph is not a function. For example:
Source: Wikipedia
