As this idea percolates around a number of elements - Xcrawl style dungeon-courts as practical exams is always a winner - one area that's always come up short is the actual sitting in class part of going to school. Happily, Skerples over at Coins and Scrolls has recently been thinking along similar lines, and recently posted some thoughts about a similar conceit using his Magical Industrial Revolution* setting. Of course, his version is a little more collegiate, but the system of a pass/fail roll that varies in difficulty based on the difficulty of the course is really quite intriguing. My only modification would be to encourage players to take the more difficult courses by offering small perks upon successful completion - perhaps a +1 or advantage on checks against getting lost for those who've passed "Unusual Cartography", for example. It's very tempting to rebuild the whole course list with requirements for various classes - can you really be an Assassin if you fail to pass "History of Poisons"?
On the other hand, the whole 1d100 course list is such a fine example of the kind of style this concepts requires it would be a shame to mess with it. "Nonessential Salts" indeed.