Cookie Monster: Cafeteria Manager.
Even though he's officially in charge of the cafeteria, he mostly takes care of the desserts. Never fear, though, he really knows his nutrition. His Veggie Cookies are especially delicious.
(I am not going to go into the whole "Veggie Monster" Debate, because honestly, it's ridiculous and old.)
[link] [link] [link]Oscar: Janitor.
His trash-can now has wheels so he can get around better.
Bert: English Teacher.
I thought of my 12th Grade English teacher and the role fit perfectly. Ironically, I really enjoyed 12th Grade English.
Ernie: Substitute Teacher.
Thankfully, he doesn't sub in that much. When he's not "teaching" he helps out with errands.
Louis (from Canada's Sesame Park): French Teacher.
Teaches in the school's Canadian branches in Ottawa, Toronto, and Vancouver.
Zeliboba (from Russia's Ulitsa Sezam): Russian, Environmental Club Advisor.
Mostly teaches in St. Petersburg and Moscow branch schools.
He and Big Bird form "the Tie Brothers". LOL
Herry: PE/Gym.
He's got the muscles and the kids love him!
Snuffleupagus: Guidance Counselor.
He's got the lovable personality needed for such a position.
Gordon Robinson: Science Teacher.
Teaches the Upper and Middle Divisions.
Susan Robinson: Head Nurse.
The human cast on Sesame Street is every bit as important as the Muppets, you know!
Characters (c) Sesame Workshop and PBS
Sesame Academy concept and Art (c) Able Tong 
`ChewedKandi has certainly gone out of her way to keep the vector community on the right path. Always making sure that her talents are infinitely scalable, Sharon has put her bezier curves to excellent use, and firmly anchored herself as an inspirational leader. We're absolutely delighted to bestow the Deviousness Award for June 2013 to `ChewedKandi. Congratulations, Sharon! Read More
Sta.sh
Oscar: I can see why he would be a janitor, seeing as he picks up trash all the time.
Bert and Ernie: I can't quite see why Bert would get the higher position if Ernie is the more prominent of the two.
Louis: Never heard of him... besides, Sesame Park was discontinued...
Zeliboba: Never heard of him either... I don't read much about International Sesame Street
Herry: Sure, a big and strong guy like him would make an excellent PE coach. Too bad he's retired now...
Snuffy: Do you think he would be shy around students?
Gordan: Making a science teacher isn't a bad idea.
Susan: Sure, making her a nurse is a great idea, too.
PS: I'm thinking about faving these eventually, because these are some good concept sketches.
I don't really know much of international Sesame Street myself. All the information I know, I read off of the Muppet Wiki.
Gordon and Susan were actually already a teacher and a nurse, so I didn't really do anything! LOL