When students have to choose between Larry Tudgeman and Claire Miller for class president, Lizzie decides to run for office. Although, she finds that gaining the favor of all her classmates won't be easy; Matt gets an imaginary friend, and Lizzie uses this to her advantage to tease her little brother.
Lizzie becomes friends with a bad girl and develops bad habits and a bad personality. Miranda and Gordo are concerned with this and decide to help Lizzie become her old self. Matt is given the freedom to stay up late at night, but after initial euphoria, he starts having problems with staying awake during the daytime. Miranda and Gordo create a short video to convince Lizzie to be good again.
In order to stand out of the crowd, Gordo sports a 1960s attire (including a Sinatra fedora) and starts listening to the Rat Pack. But he is disappointed when the trend catches on with the whole school, including Lizzie and Miranda. Matt and Lanny try their hand at creating a record in order to get their names featured in the Guinness World Records
Lizzie gives Miranda a bad review when she plays the lead role in the school play. Miranda soon realizes that singing is her main talent, rather than acting. Matt and Lanny want a pair of walkie-talkies, but Matt's parents refuse to pay for it. So Matt sells everything he owns, including his bed and clothes, to get the money.
Lizzie has to attend a class charity drive and looks forward to spend the whole day with Ethan. At home, Matt irritates Lizzie with his magic tricks and he handcuffs himself to Lizzie and loses the key. Meanwhile, Jo finds the key and decides to remain silent about it so that Lizzie and Matt learn a lesson about family bonding, getting along, and looking out for each other. Lizzie has a hard time keeping Matt hidden from Ethan for the whole day leading to embarrassing situations.
Lizzie and her friends lie at their homes and sneak off to see an R-rated movie that everyone else at school has seen. While at the movie theater, Lizzie saves a man who is choking on a candy ball and gets interviewed by a TV crew. Lizzie's parents come to know of it and Lizzie gets busted. Meanwhile, Matt is having a fair at school and Jo decides to build a velcro-wall in which kids can jump onto.
Lizzie and Miranda feel neglected, when Gordo spends more time with his new girlfriend, Brooke (Kyla Pratt). They are unable to come to terms with the fact that Gordo has a girlfriend now and he is drifting away from their group. Meanwhile, Matt learns about "percentages" from his father and starts accepting bets from his friends, but he eventually lands in trouble when his mother finds out about this.
Gordo becomes Ethan's math tutor because he needs the money to buy a new stereo. However, once Lizzie shows Ethan an easier way to do math, he decides he wants Lizzie as his tutor, and not Gordo. Meanwhile at home, Matt and his friend Oscar try to emulate superheroes by trying to help people. But their noble intentions are not well received by people around them as they unknowingly cause harm to them.
A big-time movie director offers to follow Gordo around to see a day in the life of a regular kid. Gordo starts saying rude things to the camera, though, and even coaxes Lizzie and Miranda to tell each other's secrets in front of the camera during which it is revealed that Lizzie had a crush on Gordo in the 4th Grade. Meanwhile, Matt gets blamed for all the troubles created by Melina and he admires her qualities as a troublemaker.
Lizzie is selected as a model to participate in a fashion show presented by Teen Attitude magazine at a local mall. Her modeling stint earns her fame in the school but she is annoyed when everyone starts treating her differently because of her new status. Meanwhile, Matt and Lanny buy a hammock from a shop but when it turns out to be defective, the shopkeeper refuses to take it back and give them a refund. Matt and Lanny then decide to teach him a lesson.
Lizzie wants to become the "Dungeon mistress" for the 7th grade Halloween fright night at school. However, Kate becomes the dungeon mistress and Lizzie is forced to become a clown. Peeved by this, Lizzie, Gordo, Miranda along with Matt devise a plan to embarrass and humiliate Kate in front of the whole school.
Hoping to win a trip to Miami, Florida, Lizzie, Miranda and Gordo team up to enter the school's "Fact-athlon" contest. Mr. Digg coaches them for the quiz in an unconventional way but they eventually end up losing. Matt and Lanny hire a drummer and start their own rock band, but in the end they call it quits.
Lizzie discovers that Larry Tudgeman has a romantic crush on her and when he asks her out, she reluctantly agrees to go out with him. Surprisingly, Lizzie enjoys the date, but eventually in the end, they part ways. Meanwhile, while cleaning up some junk, Matt and Sam find an old Soap-Box Derby racer and decide to restore it.
Gordo becomes obsessed with a Dungeons & Dragons type board game which was gifted to Lizzie by her grandmother. His obsession causes his grades to drop and Lizzie and Miranda take the help of Matt to bring Gordo back to his senses. Meanwhile, Matt has to observe wildlife for school project but eventually, Sam and Miranda's father end up climbing a tree and watching a bird's nest.
After being absent from school, Lizzie finds out that her project partner is none other than Kate Sanders, who was also absent on the same day. After their initial hostility, they both start getting along together. But after the project is over, they both take potshots at each other but not before sharing a secret smile and realizing that they still have a bond between them. Meanwhile, Matt is convinced that he has psychic powers and has a hard time convincing his mother about it.
Miranda is romantically smitten with a boy in her class, but is too nervous to talk to him. So, Lizzie decides to help her out. A misunderstanding leads the boy to believe that Lizzie has a romantic crush on him. Gordo is sick of listening to all the girl-talk between Lizzie and Miranda and decides to indulge in some male bonding with Matt.
Gordo installs video cameras all around the school, revealing embarrassing secrets about the students. Further, he plans to enter his film into the district film competition. Miranda gets upset on hearing this as the film showed her in bad light. However, Gordo pleases all when he showcases the film without revealing anyone's identity. Meanwhile, Matt decides to become a stuntman and tries out various stunts.
Gordo feels self conscious when he sees Ethan Craft and Larry Tudgeman growing up sooner than he is. He tries to be "manly" by trying to do manly things but in the end he decides to have a Bar Mitzvah which would initiate him into adult life. Meanwhile, Jo becomes fed up with her husband not taking things seriously when Matt misbehaves and goes on strike forcing Sam to deal with their son's behavior.
Lizzie has her first boyfriend, named Ronnie, who is the local neighborhood paper boy. Lizzie is completely head-over-toenails in love with him, and Miranda and Gordo are fed up listening to Lizzie talk about him all the time. However, Lizzie is heartbroken when Ronnie breaks up with her to go out with a girl from his school. In the end, Lizzie is consoled by Gordo. Meanwhile, Matt needs only one baseball card to complete his card collection but only Melina has it. Melina agrees to give the card to Matt, but only if he does her homework and other chores for her.
Lizzie, Miranda and Gordo are obsessed with a Mexican game show, "El Oro de Montezuma" ("The Gold of Montezuma"). Miranda's cousin Carlos from Mexico City is scheduled to compete on the show and Lizzie and her friends decide to be in his team. Meanwhile, Matt and Lanny play an extreme version of Hide and Seek.
Lizzie and her mom become best friends after reading a book in social studies. She even convinces Gordo and Miranda to bond well with their parents. But in the end, Lizzie realizes that it would take some time to be more intimate with her mom. Meanwhile, Matt and Lanny find a chimp which creates havoc in the house, for which they both are blamed.
When Kate dislocates her shoulder during cheerleading practice, Claire usurps Kate's position as captain. Lizzie helps Kate regain her popularity and a place in the cheerleading squad. Matt is excited to be in a school play and acts arrogant about it. He starts bossing his parents and Lanny around, but in the end he loses his voice and learns a lesson in humility.
Miffed with her parents for not raising her allowance, Lizzie gets her first job as a busboy at the Digital Bean. But to Lizzie's surprise, it is a lot worse than she ever suspected it would be. Matt has some problems with Melina and turns to Miranda for advice. In the process, he develops a huge crush on Miranda, much to her horror and Gordo's amusement.
Lizzie, Miranda and Gordo have a fight and stop talking to each other. Meanwhile, Kate and Gordo, Miranda and Larry, Lizzie and Ethan, are paired up for a treasure hunt-styled school project. Matt comes to know of it and, unknown to them, beats them to the finish line. As the school project progresses, Lizzie, Miranda and Gordo realize the worth of their friendship and renew their ties.
Gordo encourages Lizzie to finally do something about her crush on Ethan Craft -- that is, ask him to the Sadie Hawkins Day dance. When Lizzie asks Ethan for the dance, he disappoints her by saying he likes her as a 'friend', and does not want to risk changing it by going out with her. Lizzie then tries to change her image in order to please Ethan, but he still lets her down by saying they don't have a lot of chemistry. Matt and Lanny open a club in their backyard and their beverage becomes quite popular. But in the end, they are forced to shut it down.
In this Freaky Friday-inspired episode, Lizzie and Matt switch bodies for a day. Matt (in Lizzie's body) and Lizzie (in Matt's body) go to each other's school and end up in amusing situations. They both solve each other's problems at school but the next day, they return to their normal selves, leading Lizzie to wonder whether it was all a bad dream.
Lizzie has a hard time standing up for Miranda when she is accused of shoplifting. This creates a rift between both of them, causing them to choose different dance partners in their dancing class in P.E. However, in the end both realize their mistake and become friends again. Meanwhile, Matt hosts a talk show along with Lanny on the internet.
Lizzie starts feeling inferior when she realizes a lot of the other kids around her have special talents and skills that they've developed, including Gordo with his film making and Miranda with her violin. Meanwhile, Matt is scared after watching a horror movie and is convinced that their house is haunted.
While Lizzie and Kate are stuck working together for the Spring Fling committee, Lizzie sees Kate knock over the bust of the school's founding principal. When Principal Tweedy (Phill Lewis) discovers this, he cancels the Spring Fling unless the person responsible comes forward. Kate keeps quiet so Lizzie decides to take the blame and is excluded from attending the fling. Lizzie is sitting at home sad, until everyone at school comes over to her house, as they decided to have the fling at her place, while Kate is left all alone at school. Meanwhile, Matt and Lanny have a hard time sharing a bike.
Lizzie begins mentoring a seventh-grader girl named Andie (Amy Castle), who begins to mimic her characteristics and behave like Lizzie. Initially flattered, Lizzie starts to dislike Andie and advises her to stop aping her blindly and be herself. Finally, Andie ends up being Kate's protege. Meanwhile, Matt must earn a merit patch with his Wilderness Cadets group, or he would be demoted. Sam tries to help, but ends up harming himself.
Miranda has a misconceived notion that she is fat and begins to skip meals to look slim for a music video directed by Gordo. Miranda begins to develop an eating disorder and Lizzie and Gordo are concerned about it. However, in the end Lizzie convinces Miranda to be comfortable with her body and persuades her to stop dieting. Meanwhile, Matt shows a great artistic potential and his parents encourage him to pursue it. However, he gets into trouble when he trashes their house and uses their family car as canvas for his paintings.
Gordo skips a grade and gets promoted to high school. After initial euphoria, Lizzie and Miranda start to miss Gordo. Gordo too feels lonely at the high school but pretends to like it in front of Lizzie and Miranda. In the end, he returns to middle school. Meanwhile, Matt and Lanny plan to try out for the cheerleading squad at school but Sam feels that it's not a "manly" thing to do. Sam tries to lean away Matt from cheerleading by doing some "manly" things with him, but in the end he changes his mind and encourages Matt to try for cheerleading.
Kate is having a big birthday party and she invites everyone from her class including Lizzie, Miranda and Gordo. But Lizzie and Miranda's parents refuse to let them go to the party as there would be no adults around (and Kate's cousin Amy (Haylie Duff) doesn't make good chaperone material). So, Lizzie, Miranda and Gordo lie at their homes and go to the party anyway. But the party goes horribly wrong and Lizzie calls her mother for help. Eventually, all three are grounded for lying and going to the party anyway. Meanwhile, Matt and Sam are selected to star in a commercial for Cardio Punch Sports Drink.
Lizzie starts an advice column on her school's website, but soon finds it difficult to handle when her good intentions backfire, especially when Gordo's liking her as more than a friend, is almost accidentally revealed to her. Meanwhile, Matt feels threatened by a new prankster in the class who is gaining more popularity than he is.
Lizzie and her friends are graduating from middle school. They all sign each other's year books, except Gordo, who is unable to decide on what to write in Lizzie's book. He eventually writes something heartwarming and is rewarded by a kiss from Lizzie while posing for the class photograph. Meanwhile, Matt is unable to bear the summer heat at home, and thinks of various methods to keep himself cool.
The McGuire family members (all except Lizzie) are all psyched about making their annual journey to Grubby Gulch, a "Wild West" theme park, after missing last year's trip. Lizzie, Miranda, and Gordo are reluctant to go for the trip, but Matt is very excited about it. Lizzie, Miranda and Gordo meet a boy and a girl respectively at the cafe, and arrange a date at the mall, but Lizzie's parents won't let them go, so they feign illness to go on the date.
Lizzie, Miranda and almost every girl in their class have a crush on their new English teacher, Mr. Keith, who is from Scotland. Meanwhile, Fredo the chimp comes to stay at the McGuire's home and Matt is not happy with it. With some intervention from Jo and Sam, soon Matt and Fredo are getting along very well.
Miranda is throwing a big house party, and refuses to invite Larry. Lizzie feels bad about it and decides to give him a makeover and sneak him into the party. Meanwhile, Matt and Melina make friends with an elderly couple as a part of a school project and find that the old couple are just like them.
After setting a new school record in gym and then beating Ethan Craft in arm-wrestling, Lizzie is invited to play touch football with the "cute guys". But Lizzie is worried when Ethan calls her a "dude", and she feels that she is losing her feminity by playing football. The gym teacher, Coach Kelly, reassures her, and also reveals that Ethan calls everybody a "dude". Unknown to Matt, Fredo the chimp completes his math homework, which gets him good grades in school and praise from his parents.