The bigger subjects are:
Search and Rescue - lots of lists, protocols and procedures
Communications - everything from hardware to phraseology
ATS - a kind of all-encompassing subject about the job and how it's done
Just wait until you start Separation Standards 1 & 2
If you want to scare yourself have a look at MATS chapter 10
Don't worry too much, it all seems hard at first however you will get there in the end.