The lecture includes topics: graphs of line, function notation. It can be used as review or as a lesson to introduce function notation. The examples are practical and last one is real life application of using graphs and functions. In general, it gives overview of graphs and functions as special kind of relations.
In case students are confused how to determine is relation a function or not, I suggest the following approach.
Let consider each element of domain represent a child and each element of range represent biological mother. So, logically, is it possible for two different kids to have a same mother? Yes, students would agree. It is a functional situation, so this is a function. In opposite way, is it physiologically possible for one child to be born by two different mothers? No, they would say, it is not functional at all. It is impossible. So, they should conclude: if one element of domain has two different corresponding elements of range - it is not a function. Obviously, they suppose to know the definition of domain and range which I included in my notes.