With the family tired of watching reality television, Bart suggests a satellite dish. Homer has an idea to raise money. Horse racing. Flush with cash, Homer buys a system. Watching hours upon hours of bad TV, Bart neglects to study for the Elementary School Achievement Test. He fails so badly that he gets dropped back to third grade. Meanwhile, Lisa does so well, she gets moved up to third grade.Haven taken all the tests of third grade before, Bart excels. But Lisa struggles to catch up. On a field trip to Capital City, the class has a project to design a new state flag. Bart sabotages Lisa's design, humiliating her in front of Governor Balley.Bart and Lisa break into a fight and miss the bus back to Springfield.
Principal Skinner informs Homer and Marge that the kids are missing. Meanwhile, Bart and Lisa spend the night in the woods. A family of hillbillies comes across Bart and Lisa and drives them back to Capital City, where they're reunited with Homer and Marge. Principal Skinner tells Bart and Lisa they should return to their respective grades to maintain the status quo.