Building Blocks - Function Notation

I have concentrated on the algebra rather than linking to graphs of functions as I’m not sure at GCSE that the graphs are overly helpful for solving function notation problems; I will eventually get on to transforming functions which will tackle this (size could be an issue in the format though). This goes from simple function machines, through substitution, rearranging formulae and links them to functions questions. This started off as a request from a former colleague who bemoaned the lack of function notation resources, which is a fair point at present, I think.