Ask yourself an interesting, practical question, and see if it's not about the relationship between variables.
To operate well you have to understand the world in which you work. To understand, we need to describe. There are many ways to describe the world, and a mathematical descriptions offers one of many possibles views. However, it is an extremely powerful window through which to observe the world:
We understand functions as descriptions and summaries for the world about us.
Functions, whether you recognize it or not are, are encountered on a daily basis. The next section provides some examples of functions, found in everyday life and is intended to demonstrate to you that fact that your are indeed likely to be familiar with functions even if you do not explicitly realize it.