In the movie, Professore Sperelli (Paolo Villaggio) arrives in Arzano from Northern Italy and then strives to do his job well locally. He ends up learning as much (or more) from his students as they from him while we all learn more about Italy and the modern world.
There's almost always a built-in storyline when cultures collide. There's so much rich material that lends itself to comedy in movies and books like Ciao, Professore! -- and tragedy in other works -- just as in life throughout history and around the globe. Here we have North and South Italy, but it could just as easily be set in the USA, or even within an individual state like Michigan ("Up North" contrasted with "Southeast Michigan" aka Detroit and its environs, or as opposed to "Western Michigan."). It could be set in England (London, the South and the North Country) or Germany (Bavaria and the Baltic or North Sea coast). Luis Buñuel inserts jokes about South-North differences in several films, whether set in Mexico, Spain or France. Clearly, cultural nuances and varieties make for a lot of interest. Why else would we travel? Indeed, why else would immigration and migration be such a big deal if such were not the case?
*To quote from one pupil's essay on Switzerland:
Switzerland sells arms to the whole world so they can kill each other, but Switzerland doesn't ever have even a small war. They build banks with all their money. But not good banks. The banks are for bad persons, especially drug addicts. Criminals from Sicily and China put their money in these banks. The police go and ask, Whose money is this? and they say I don't know, I'm not going to tell you, it's none of your damn business, the bank is closed. But the bank is really open!! (For the whole essay, see http://www.napoli.com/english/blog26.php)