The final section of the Evolution Topic discusses the Advantages of classifying organisms, and how we classify organisms.
Hank gives a good overview here
The slideshare we referred to in class is given here
So now we look towards the Additional Higher Level work in this section and we start with the Hardy-Weinberg Principle.
A nice introduction is given by Hank from Crash Course Biology
Jason de Nys has done a Nys (pardon the pun) slideshare presentation
If you want to know how to solve H-W Problems then a nice tutorial is given below