I don't know why this film is so underrated. For me, this film is special. This is not an ordinary one, even inside of the amazing world of Tati's films (there is no such a thing as an "ordinary film" when talking about Tati). If you take it seriously, not as a simple piece of comedy sketches, this is a short about Tati's obsession: observation. As a matter of fact, in this short, Tati's character makes his point about it: "this is a class about observation".Observation of details as in his whole work, is the clue to understand the film or, at least, make it enjoyable.
Despite the fact of not being directed by Jacques Tati, this is also a film about Tati's peculiar style, especially if we think about the black and white scene that reminds us of his first works: "School of Postmen" and "Jour de fête". The whole short is like the beginning of "School for postmen", when a postman is leading others in their training of mail delivering, but this time with a special and simple "reflection" (one might say): all those things that make Tati's films charming and funny are based on that little thing called observation.