I don't understand the relevance of comparing a current system to the one i'm going to build. The current system is completely different!

Okay, just take a step back for a minute. You're thinking too hard about what looks good on paper and not thinking logically. This is a coursework question and so you must write and explain like the examiner is a child. 
The current system may be lacking or not similar to what you are going to be developing.. but, the new system must have a doppelganger in the current system (or as close to one as possible). For example, if you are developing a new database for registration of each class, instead of thinking "There is no current registration system?" Think about how the teacher may check your presence. Maybe she verbally checks, or maybe she has an unofficial notebook?
Also another think to remember a system is more of a process to get a task done rather than an encapsulated piece of software or hardware, going back to the previous example. The teacher may have a current registration system, but that may go beyond the registration software she has.. she may write down the names, get it approved by a head of department, enter it into the software and then print it off. That whole series of input-process-outputs makes up the "registration" system.