"Lisa Simpson, This Isn't Your Life" is the fifth episode of Season 22.
When Lisa discovers that Marge's good grades slipped away when she met Homer, Lisa wants to avoid turning out like Marge. To do so, she is enrolled at Cloisters Academy and soon learns the truth why Marge became a dropout. Meanwhile, a series of coincidences in which Bart gets the better of Nelson leads everyone to consider Bart as the new school bully.
After finding out that Maggie is displeased about missing one of the collectible Happy Little Elves, Homer drives the family to a Texxon station. This leads to Homer continually buying gas to try and win the rare Baby Must Have toy. After failing, they navigate through the district of town where Marge grew up. While visiting the old Bouvier house, Lisa discovers Marge was a top-grade student.
Meanwhile, during a stunt through the poorly-drained school playground, Bart splatters the mud over Nelson. However, when Nelson attempts to punch him, Bart slips and inadvertently kicks Nelson in the face, leading Bart to become the new school bully. Later on, Lisa asks Principal Skinner about it, and he confirms that Marge was very intelligent in her infancy. However, this has not prevented her from becoming a stereotypical stay-at-home mother. Skinner warns Lisa that she will likely have the same future because, despite her potential, Skinner realizes by experience that children often have the same fate of their parents.
Lisa discovers that Marge's grades plummeted after she met Homer. Her father tells her that everyone meets their 'Homer' eventually, and Lisa will be no different. Hearing this, Lisa aims not to get distracted, by clearing everything in her room out, including her saxophone. Marge finds out from Homer that Lisa wants to be nothing like her and is distraught. Despite her best efforts, Marge is distant towards Lisa while very attentive towards Bart for wanting to be like her. Although inept, Homer does his best to cheer Lisa up by leaving a seven of clubs in her lunch bag when Marge turns against her.
At school, Nelson confronts Bart at the tetherball, where Nelson hits it by mistake and knocks himself over, and in the hall, where he walks into a locker and gets trapped inside. Soon Bart becomes fearful when getting tailed by Nelson with the intent of getting picked on by him.
One day, Lisa finds out about Cloisters Academy after observing a bus at a traffic light next to the school bus. She sees a lot of children into their studies with a small orchestra playing classical music to help their atmosphere. Seeing the school as her only chance to having a successful future away from the home, Lisa tries to persuade her parents to let her go. At first, Marge refuses because of the high tuition fees that the Simpsons can't afford. When the principal at Cloisters makes a crude comment about Lisa remaining at Springfield Elementary, Marge is upset and Homer realizes that look that means she will never take no for an answer. Being sent outside, Lisa and Homer wait for the outcome. After waiting momentary, the principal and Marge comes out of the office and the principal tells Lisa that Marge convinced him to reevaluate her record and she is offered a scholarship there.
Later on, Bart tells Marge about his bully problems with Nelson and becomes frustrated when she mistakenly assumes it is Milhouse. Marge tells Bart to compliment Nelson for having faith in him. Bart tries to prevent an attack by making Nelson feel good about himself. This works when Bart mentions his appreciation with Nelson for hiding his face during school pictures.
Lisa discovers that she has not been offered a scholarship and that she was only accepted due to Marge offering to do all the school's laundry. Also, to make matters worse, she has become an overtired, overworked drudge as a result. Concerned about her mother's health, Lisa tells Marge that the kids at the school are snobs and she would rather turn out like her than them. While hugging Marge when she isn't looking, Lisa has a sad and guilty look on her face. She was lying to make her mom happy and is sadder when she realizes she had to give up her own future dreams of being successful without distractions.
Homer steals a Baby Must Have from the Texxon store to keep Maggie happy. Raphael, the store manager, arrives on the scene at the Texxon and asks if the robber took any money. When told it was just the toys, he says "He did now!" and the episode finishes with Raphel stuffing his pockets out of the cash register.