"Stealing First Base" is the fifteenth episode of Season 21.
When Springfield Elementary's two fourth-grade classes have to share desks rather than pay for a substitute teacher, Bart falls for his new deskmate, but after he kisses her, she starts sending him mixed signals; Lisa gets advice on how to handle being a female overachiever...from Michelle Obama.
Bart's fourth grade class is merged with another fourth grade class when Edna Krabappel is absent. The teacher is Miss Audrey McConnell from Bart vs. Lisa vs. the Third Grade. In the crowded classroom, Bart is forced to sit by a new student named Nikki. At first they dislike each other, until Nikki admires Bart's artistic skills. Bart seeks romance advice from Homer, who passes him off to Grampa. Grampa advises Bart to kiss Nikki. However, when Bart kisses Nikki after the two went skateboarding, she recoils in disgust. Nikki's parents, who have powerful ranking statuses, threaten to sue the school unless it enforces a "No-Touch Policy". The school is then forced to put on a school play in which Skinner and Willie are forced to kiss each other to the amusement of the students. After this, Bart is surprised when Nikki kisses Bart while hiding in his locker. Later on, Michelle Obama makes a surprise visit to the school and gives a speech defending Lisa for being an overachiever.
Bart and Nikki have been watching this speech from the roof, and Bart comments that he's happy that they're dating. Nikki then changes her mood and tells him they're not dating. They argue and Bart stumbles and falls off the roof. Bart is not breathing, but the school's "no touch" policy prevents anyone from performing CPR. Nikki defies the policy and revives Bart (who, while unconscious, dreams a montage of kisses reminiscent of Cinema Paradiso). After the policy is banned, Nikki's mood changes yet again and Bart remains in a state of complete confusion over her behavior.
The kiss montage contains "scenes" from Here to Eternity, Gone with the Wind, The Quiet Man, Lady and the Tramp, Planet of the Apes, On Golden Pond, Ghost, Spider-Man, Star Trek (the 2009 film), Beauty and the Beast (TV series), The Public Enemy, WALL-E, Alien 3, The Godfather: Part II, and an All in the Family The sequence, and the accompanying musical score, are a nod to Nuovo Cinema Paradiso, directed by Giuseppe Tornatore, with score by Ennio Morricone.
Meanwhile, Lisa becomes more popular when she receives an F on a test, but becomes unpopular again when it is revealed that she was given the failing grade by mistake. She blogs about being ostracized as an overachiever, and her post is noted by a mysterious blogger known as FLOTUS1. FLOTUS1 ("First Lady of the United States 1") turns out to be First Lady Michelle Obama, who drops by Springfield Elementary to give a speech about the importance of academics and recommends that the students be nice to Lisa and other overachievers, including Martin Prince and Allison Taylor.
Throughout the episode, Nelson has befriended a blind boy and teaches him how to laugh at the misfortunes of others. At the end, the blind boy tricks Nelson into believing that a punch he sustained after insulting Nelson restored his sight. When he reveals this to be a prank and laughs Nelson's signature "haw haw," Nelson tearfully states that the student has become the master.