I can't remember if I've ever suggested this idea, but I wonder if a Muppet high school show would be a good series. It would have the Muppets as teachers, teaching new students (plus Robin and maybe Bean Bunny). Kind of like how Tiny Toons had the Looney Tunes as teachers, though this would focus more on the teachers (the long-established characters) than the students (the new characters). Though have there ever been any high school shows that have plenty of teachers and students AND give them all plenty of balanced focus (TV Tropes points out that most TV high schools only have two active teachers)?
Or maybe it'd be better as a one-time special or a series of direct-to-video projects.
But there are many possibilities for teachers. Kermit could be the principal, or he could teach English (or maybe be a swimming coach). Sam the Eagle could be the history teacher (an American history teacher), or a Government teacher, or a theater teacher (trying to get in more dignified shows), or maybe the principal. Miss Piggy could teach fashion, Pepe could teach Math, Bunsen and Beaker can teach science and maybe audio/visual classes (or Dr. Strangepork could teach one. Or Scooter. Or, in a perfect world, Digit would teach A/V). Fozzie or Scooter could teach computer classes, Lew Zealand or Bobo (or Sweetums) could teach P.E., The Swedish Chef could teach cooking classes in addition to being the school chef (and for extra hilarity, he could be a foreign language teacher), Rowlf could teach music, Gonzo can teach art (and maybe also theater), Beauregard would be the woodshop teacher (in addition to school theater stagehand and janitor, if George isn't the school janitor), Bobby Benson could teach child development, Crazy Harry can teach construction classes... It would be hard to figure out what The Electric Mayhem would teach. Yeah, there's music, and maybe one can lead band classes, but I already listed Rowlf for music, and while there could be other music teachers, I don't think all six members of the Electric Mayhem should teach music, unless some are teaching assistants.
Another option for the principal would be for J.P. Grosse to be the principal, and maybe have Kermit as vice principal (or if Kermit is principal, have Scooter be vice principal). Or the principal could be an unseen character whose voice is heard giving announcements. Matt Vogel could try his best Jerry Nelson announcer voice for this character, and he could be called Principal Nelson. Though The Newsman would also be a good character to provide school announcements. The receptionist can be either Mildred or Janice, and councilors could include Pops, Uncle Deadley, Link Hogthrob, Sweetums, and Walter (or Walter could be Kermit's teaching assistant).