What 27/09 said...
Back in the "Good ole days"™, schools could just sign up anyone and everyone. A few bitter parents kicked up a fuss when they discovered their precious boy/girl wonderkinder now had a student loan north of $100k, a relatively worthless aviation diploma, a cpl, an MEIR, ATPL subjects, 250hrs TT and pretty poor job prospects...
There were also a large number who joined up, did the flying and didn't bother with any of the diploma coursework...
The govt, then decided that aviation placements that qualified for full funding would be limited to a set number of spots each year, and a schools allocation would be dependent on previous years completion rate (including diploma course work)... Ostensibly, to fix the imbalance between supply and demand of pilots.
Around this time, the bigger schools realised it was in their best interests to ensure that anyone signing up had a better than average chance of passing so they wouldn't lose any of their allocated positions (read as: easy income). Thus, the concept of "interviewing" for flight training was born.
It is really just an evaluation exercise no different to interviewing for a cadet scheme or even for a job. Probably even helps expose the prospective student to the ongoing evaluation that one can expect from a career in aviation.
My advice, basic (mental) maths, some of those "next in the sequence" type logic puzzles and also have a think about your motivations for wanting to be on the course. Chances are there will be a few "so, why do you want to be a pilot?", "why do you want to instruct?", "where do you see yourself in 10 years?", ":what are you hobbies?" Type of questions as well. It isn't just all about the maths
Good luck
