Åk 6–9
1.1 Introduction
The word function means relation. A relation is a connection between two things.  Imagine that you have one machine. For the machine to work, you need to give it information, and that there is a relation between the information that you give it and what the machine does.

A car is a machine, and the car will work differently depending on which information it gets.  There is a relationship between you giving it gas, hitting the break, etc and what the car does.  What the car does is the function of the information it gets.

Foto: Christian Almstedt,

The Function Machine
Imagine that the machine to the right is programmed to do some function.

There is a relation between the numbers that we feed it and the numbers we get out.  The machine handles every entered number with the same rule.  This relation is called a function.

Foto: Fredrik Enander