When Helga loses her pink book, full of love poems about Arnold on the bus, it ends up in Arnold's hands. Now Helga must get it back before Arnold figures out who wrote the poems.

The kids are really looking forward to their field trip to the aquarium - especially when they remember the scary Lock Jaw from their last trip. But, when they get there, they see that Lock Jaw isn't really that scary. Arnold notices how neglected the old turtle looks, and returns later with Grandma to set it free.

While Helga tries to find the perfect gift for Arnold, Arnold tries to find Mr Hyunh's long-lost daughter.

Arnold has trouble with the basketball coach and his favored son.

When Arnold's pigeon gets sick, he takes it to "Pigeon Man", a person surrounded by pigeons who lives in a rooftop.

Eugene is accused of pulling the fire alarm. In the school court, the jury thinks Eugene is guilty except for Arnold, who believes there is a shadow of a doubt.

The kids try to get in the book of world records so much that they would do anything, including most people on a one-person bike and the longest game of Crack-The-Whip.

Arnold hits Harold with a baseball, so Harold promises Arnold that he'll beat him the next day.

Arnold and the gang must stop Big Bob from chopping down the oldest tree in town.

When the kids make their new teacher, Mr. Simmons, quit his job, the replacement makes them realize what they lost.

Gerald's secret is revealed; he doesn't know how to ride a bike, so Arnold teaches him how.

Arnold and Gerald compete against Helga for the school newspaper.

Schoolyard tradition has it that on the first Monday of June each year, the fifth graders throw the fourth graders into trash cans. So, Arnold and Gerald try to make a run for it. As more people are thrown into trash cans and the fifth graders know all the routes, Arnold and Gerald find out eluding the fifth graders is harder that they thought.

An organ grinder's monkey kisses Helga, who's convinced she has caught 'monkeynucleosis'.

Arnold and Gerald do a spot of fishing, determined to catch the pond's biggest fish, the legendary "Big Caesar".

The new girl is teased at school by Helga and the other girls, but she's soon accepted by everyone.

Arnold and Gerald bunk off school, but their day is ruined by their fear of being found out.

In this variation of "The Tell-Tale Heart", Phoebe plagiarizes from a poetry book and uses one of the poems as her entry in a poetry contest. She wins, with her prize being a trophy resembling poet Emily Dickinson. Then, the trophy haunts Phoebe into confessing.

Wolfgang and his gang of fifth graders challenge Arnold and his friends to a football game, but he has to first persuade them that his plays are good enough for them to win.

Gerald becomes an entrepreneur out of selling watches until the market becomes saturated.

Rhonda and Nadine fall out over working on a project at school, leaving Arnold to work with both of them separately.

Arnold and Gerald send the neighborhood alien crazy as they broadcast a mock Halloween radio show.

Helga uses Stinky as her boyfriend to try to make Arnold jealous.

Arnold develops a crush on Miss Felter, a substitute teacher, thinking he is having dinner at her house, only to realize that the one she invited was her fiance, whose name is also Arnold.

Helga and Arnold fall asleep and have their own "parody/dream" of the opera Carmen.

Arnold and a descendant of his grandpa's arch enemy, Rex Smythe-Higgins, compete in a boat race.

Teachers of Arnold's school go on strike because of inadequate funding; He and his friends are on cloud nine, only to find out that every lost school day will be taken from their summer vacation.

After creating an idea for a parade float, Arnold is confident of it showing up in a parade.

While feeling the effects of laughing gas, Helga leaves a confessional message of love on Arnold's phone machine. She then has to get into the boarding house in order to erase the message.

Gerald's voice is deepened after having his tonsils out, just a few days before the school recital.

Sid pretends that Arnold's room is his, since he's ashamed of showing his real room to Lorenzo.

Patty challenges Helga to a fight after Helga gets on her last nerves by picking on her once too many.

Stinky's simple life changes after he becomes the surprise new spokesman for Ya-Hoo Soda.

Curly gets enraged after a minor playground mix up. He locks himself in the principal's office and refuses to come out.

Principal Wartz gives Sid a detention believeing he placed fake vomit so he could trip over, even though it wasn't Sid who put it there. As a result, Sid seeks revenge and reates ""Revenge Doll"" of Wartz's face, like they do in tribes. He thinks he killed Wartz with the curse. Arnold thinks he's paranoid, even though there are a few clues hinting out that Wartz is dead.

A roller coaster breaks down while Eugene and Arnold are at the top of its tallest drop.

After the results of an aptitude test are announced, Harold gains self-confidence and Helga feels dumber.

Arnold finds out Iggy wears bunny pajamas with feet in them, and Arnold accidentially spills the beans to Sid and Stinky, ruining Iggy's cool image.

Bob hires a nanny to help Miriam around the house, much to Helga's dismay. From this moment on, Helga attempts to scare the nanny away.

Harold is invited to Rhonda's party and befriends the female bully, Big Patty.

The Coach wants to remarry Tish and asks Arnold to be his best man. Along the way, Arnold teaches the coach a thing or two about love and sacrifice.

Rhonda holds a cool-people-only party at her house. In retaliation, Arnold and his friends hold a "geek" party on the roof of his boarding house further up the street, leaving Rhonda's party deserted.

Helga, lost in a love reverie, writes 'Arnold loves Helga' on a wall, but changes the name to 'Lila' when the kids approach. Lila thinks that Arnold loves her until he explains the mistake. Then he falls for Lila and she is forced to break up with him.

The kids compete in a grand prix race against each other.

Arnold and Helga both think they are having the worst Thanksgivings ever. Arnold's Family are celebrating President's Day, and Olga is at the Pataki house. When Arnold and Helga go to Mr. Simmons' house, they discover he has a obnoxious family, so they think their families aren't so bad after all.

Helga tells jokes about her classmates, who take offense to it.

The town is flooded and Arnold's class is trapped in the school.

Arnold, Grandpa, and friends reenact the Pig War.

As a science assignment, Arnold and Helga have to work together, and get along with each other, for 24 hours in the Sunset Arms greenhouse.

Lorenzo, a neurotic rich kid, comes to P.S. 118. All the kids try to help him become an average kid.

Arnold snaps at school after Helga tries his patience once too often.

Arnold is in charge of the school dance. He books has-been singer Dino Spumoni, and when he sings a depressing "good-bye" song, all fingers point at Arnold.

The school is doing the play "Romeo and Juliet". Arnold lands the role as Romeo so Helga will do anything to beat out other girls to get the part of Juliet, so that she can kiss Arnold in the final scene.

Harold, Sid, and Stinky all moon Principal Wartz, but Arnold is blamed, even though he was just an innocent bystander.

Helga's sister Olga comes home for spring break and becomes a classroom aid in Helga's class, much to Helga's chagrin.

After Sid works off a debt with loan shark Big Gino, the two become friends, but when Sid is told to give Arnold a swirlie, he has to choose between the two.

Gerald's older brother Jamie O has a sudden burst of kindness when he finds a girlfriend, but Arnold and Gerald soon find out that the girl is just using Jamie O.

After losing Eugene's birthday party invitations, Arnold feels obliged to throw him another party, but it doesn't work out.

Stinky grows a huge pumpkin to enter in a city competition.

After Bob pops his spine, Miriam runs Big Bob's Beepers. She gets in over her head and forgets about her family.

Arnold finds out that Oskar is illiterate and tries to teach him to read.

Helga wants to show Arnold that she can be as sophisticated as Lila is by taking him, Gerald, and Phoebe out to dinner with a coupon she won. She devises a plan to get out of paying when she discovers they're at the wrong restaurant.

Phoebe is promoted to the sixth grade, but realizes that her new so-called "friends" are just using her to do their homework.

A sleep-talking Helga confides into Bob's parrot about her love for Arnold. The next day, the parrot flies into Arnold's window, and it is up to Helga to get it.

Crisis strikes when Gerald's little sister, Timberly, eats a stock of chocolate turtles that he and Arnold are supposed to sell for a local scout organization.

Helga tries to separate Arnold from Lila while at the annual Cheese Fair.

Harold, after discovering his friends think he is obese, decides to go on a weight-loss cruise. When he comes back, though, he is noticeably larger.

After Grandpa tells Arnold that he never got his grade school diploma, Arnold convinces him to come to go back to school at P.S. 118.

Arnold and Helga must care for an egg for a school project about parenting. Meanwhile, Rhonda and Harold are project partners and must also take care of an egg.

Helga becomes a model, but she quits after she gets irritated at everyone dressing like her.

Arnold's classmates are tired of constantly telling them the right thing to do, so he stops giving them advice. Nevertheless, when his classmates get into sticky situations, they are in desperate need of his advice.

After getting in a car accident, Bob and Grandpa face off on the golf green, with the loser having to pay for the damage to both cars.

Rhonda attends a finishing school, but is far from impressive with her stroppy attitude, and seeks help from fellow student Big Patty.

Arnold's bland country cousin, Arnie, comes to visit. Arnold begins to notice that Arnie and Lila show interest in each other, making him jealous.

Oskar has to take care of his infant cousin-in-law (also named Oskar), while both Susie and her cousin are gone.

Phil's twin sister comes for a visit, bringing along an unsettled conflict between them.

Arnold and the gang are part of a synchronized swimming team led by Coach Wittenburg.

After eating pork rinds, Helga sleepwalks, uttering her secret about Arnold as she does so.

Arnold, Grandpa, Grandma, Ernie, and Mr. Hyunh compete on a game show against a "perfect" family from PS 119

Arnold tells an urban legend about a decapitated taxi driver. The gang goes out, only to find the details in the story are becoming real.

Arnold and Gerald try to prove superstitions are fictitious, only for it all to backfire on them.

Arnold's Grandpa recalls his adventures as a soldier in the Second World War, outwitting a regiment of Nazis, while Gerald's dad, Martin, remembers his own time serving in Vietnam.

Helga confides in the school psychiatrist about her social life, family life, and her love for Arnold.

Dino Spumoni is found missing and then declared dead after what appears to be a suicide attempt. but Arnold finds out that this isn't the case, and he secretly lives in the boarding house, believing that his work will skyrocket in value after his "death".