For my Real World Function project I based my real world function on four National Football League teams and their corresponding hometowns.
A function is a relation for which every input there is exactly one corresponding output. A function will also pass the vertical line test. A relation is a set of ordered pairs.
The x values or the football teams(Raiders, 49ers, Chargers, Seahawks) represent the domain/independent variable, while the y values or the home cities(Oakland, San Francisco, San Diego, Seattle) represent the range/dependent variable.
In a function there cannot be more than 1 element of y for every element of x. So, if Oakland and San Francisco were listed as the hometowns for The Oakland Raiders then the graph will not pass the vertical line test, therefore it will not be a function but, a relation.