Arnold tells Grandpa he's tired of dealing with Helga's nonsense. Grandpa tells Arnold a story about a girl he had to deal with when he was a kid. / Arnold is in charge of finding entertainment for the school dance and chooses Dino Spumoni.
When the gang all decide that they are going to "moon" Principal Wartz, Arnold thinks that it's a bad idea, but ends up inadvertently getting caught and taking the blame./Olga comes to PS 118 to be a student teacher.
Arnold is the cause of two birthday party's for Eugene being a big flop./Stinky feels that he is a failure at everything he does until Arnold helps him discover that he is the best pumpkin grower in town.
When Arnold discovers that Oskar has been pretending to know how to read, Arnold confronts him./Big Bob pulls his back and cannot go to a very important meeting. Not knowing who else to send in his place, he asks Helga.
After winning coupons to a fancy French restaurant, Helga attempts to prove to Arnold that she is more sophisticated than Lila. /Helga is devastated when her patsy, Phoebe, is skipped to the 6th grade.
Big Bob gets a parrot which eventually gets on his nerves. He passes the bird on to Helga, who spills her emotions about Arnold to the bird./Arnold and Gerald decide to sell chocolate turtles to raise money for the club's ongoing go-cart project.
Grandpa returns back to grade school so he can finally fulfill his dream of graduating./Mr. Simmons gives the class an assignment to couple up and take care of an egg over the weekend to learn teamwork and responsibility.
Helga becomes the latest child fashion star and everyone loves her for her scowl and bad attitude./The gang finally gets sick of Arnold's never-ending good advice, so they all decide to stop listening to him all together.
When Arnold and Grandpa get into a fender bender with Helga and Big Bob, the typical argument of who's at fault ensues./After a confrontation at PS 118 between Rhonda and Patty, they both end up at the same finishing school.
Arnold's weird cousin, Arnie, arrives for a visit and appears to be the biggest loser to everyone except Lila, the love of Arnold's life./Oskar's wife Susie agrees to watch her cousin's baby, also named Oskar.
Grandpa's sister, Mitzi, shows up out of the blue to grace the boarding house with her presence./When Coach Wittenberg needs to form a synchronized swim team to save his job, he recruits Arnold, Gerald and the rest of the gang to compete.
Washed up balladeer Dino Spumoni fakes his own death in order to increase his record sales. Everyone believes he's dead and at the funeral, Grandpa and Arnold find out that Dino has left Arnold all his future record sales.