Bart and Lisa end up in the same third-grade class after the latest standardized test shows that Lisa got the highest grade and gets to skip ahead while Bart got the lowest grade and has to repeat third grade.

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!!"Bart vs Lisa vs The Third Grade" contains examples of:
* BigBrotherBully: Bart spends the episode as this towards Lisa. She calls him out on this, as he's suppose to protect her from horrible things, not ''bring them to her''.
* BookDumb: Double subverted with Bart. He had such a low score in his test that he was sent back in third grade, where he had better grades than Lisa. It's not that he is smarter, he just remembers the correction grid by heart (not even what they mean, he just knows question one's answer is A).
* FunWithAcronyms: Bart devises abbreviations to help remember things on the test. Lisa doesn't find it very helpful.
--> '''Bart''': Quiet Nerds Burp Only Near School.\\
'''Lisa''': Bart, I'm doing my geography homework.\\
'''Bart''': I know. That's how you remember the four original provinces of Canada. Quebec, New Brunswick, Ontario, Nova Scotia. "Quiet Nerds Burp Only Near School." Here's how you remember their principle exports: "Dogs eat barf solely on Wednesday, Mabel."\\
'''Lisa''': Stop!\\
(later...)\\
'''Bart''': Canada's Governor's General: "Clowns love haircuts, so should Lee Marvin's valet."\\
'''Lisa''': GET OUT!
* HorribleJudgeOfCharacter: The third grade teacher relies on a buddy system by pairing two students together. This backfires when she forces Bart and Lisa, [[SiblingRivalry who hate each other]], into a buddy system in class and on the field trip, where a fight between them gets them lost.
* ImagineSpot: Bart has one in class, due to TV withdrawal.
--> '''Clown''': It's finally happened, Bart: You've lost your mind!
* MoodWhiplash: Homer sees Bart and Lisa both being assigned to the third grade (though satellite TV, no less), and reacts with shock. He then changes the channel and immediately grows bored... which doesn't last long:
-->'''Homer:''' ''({{gasp}}s)'' An old army buddy is visiting Series/{{Mannix}}?!
* NoodleIncident: Bart has a fascinating one involving Lisa's bike and an unattended steamroller.
* StatusQuoIsGod: It was even [[LampshadeHanging praised]] after Bart returned to fourth-grade and Lisa returned to second.
* SadisticTeacher: Audrey [=McConnell=] (on Lisa's account).
* TookALevelInJerkass: Bart once more turns up the dial just to make sure to give Lisa a nightmare in the grade he was degraded to. He apologizes at the end.
* VomitDiscretionShot: The NBC news anchor randomly starts puking in a garbage can during a break. While we don't get to see the vomit, we see the action on screen and clearly hear realistic vomiting noises.
* WhereTheHellIsSpringfield: Springfield is in a Northern state -- that somehow has a Confederate Stars and Bars on their flag.