The Curse of the Giggling Goblin

Harry Potter and his friends are in their sixth year at Hogwarts, and Remus Lupin has returned to teach Defense Against the Dark Arts. One day, Dumbledore and McGonagall are strolling through the castle when Albus accidentally sets off a spell that turns all the professors into their sixteen-year-old selves! Naturally, chaos ensues, and while some are enthusiastic, like Lupin, others, like Snape, are feeling quite mutinous. Throughout the week, the professors must attend classes with the other students and come to terms with all the ups and downs of being teenagers again. Unlikely friendships arise, and the professors learn more about their students and themselves.

Snape's first day of class as a sixteen-year-old goes somewhat disastrously. He has to partner with Potter in Divination, then endures a very irritating Potions lesson.

Dumbledore visits with the professors, and has a conversation with Hagrid on the finer points of beards.

Minerva endures a very strange school day, which ends with something even stranger.

This chapter takes place from two points of view: Lupin's and Snape's. Harry and Severus serve their detention, while Remus and Ron decide to practice Quidditch. Later, Harry and Severus discover they have something else in common, and Severus has a little chat with Draco Malfoy.

After the Gryffindor vs. Slytherin Quidditch match is cancelled, Dumbledore coes up with a brilliant new idea.