So far this week, you have met the idea of a function machine, with input and output, and the idea that sequences are functions where the input is the position number and the output is the term. In both of these representations, the function can be considered as a process, that is, as something that you do to the input.
In Activity 1 you became more sophisticated in your treatment of the function by reversing the process. In Activity 2 you compared two functions. In Activities 3 to 6 you also saw how a function can be considered as a relationship between two quantities, that is, as something to notice and describe. This relationship stems from the structural connections that link the two quantities (which gives the position-to-term rule) and it determines how they change together. This will be the focus of the next section.