My hardest class was when i didn't actually have A class. For two years of my final degree the entirety of the coursework and examinations was case based. Meaning you would walk into an exam not knowing which one/ones of the seventeen university departments that were teaching us has been involved in putting the exam together. The biggest killer of all was the four and half hour, end of the year practical exam where anything we learned for the entire year was fair game. Not fun.