Blazed and Confused

"Blazed and Confused" is the seventh episode of "The Simpsons"' 26th season, and 559th episode in total. Originally broadcast on the Fox network in the United States on November 16, 2014, it focuses on Bart's new 4th grade teacher (Willem Dafoe), who is a terrible bully, so Bart schemes to bring him down.
Plot.
Superintendent Chalmers organizes an exchange of the very worst tenured teachers between the schools in the district, moving several teachers, including Mr. Jack Lassen to Springfield Elementary School where he will teach Bart's class. He bullies Nelson and gives Bart an embarrassing haircut, so Bart schemes to bring him down, with the help of Milhouse. Using a fake social network profile in the name of Miss Hoover, they discover that Lassen is the "Ignis" or "Chosen One" at a desert festival called "Blazing Guy" where he will set fire to the eponymous effigy.
Meanwhile, Homer has forgotten to book a campsite, which upsets Marge. Bart solves both of their problems by telling Homer to take the family to Blazing Guy. Marge, who is disturbed by the eccentric campers, drinks a cup of tea to relax, although it contains hallucinogens, making her delirious. Bart and Milhouse use fire retardant substance to make sure that the effigy will not light, therefore ruining Mr. Lassen's important moment. He is furious and grabs a burning tuba, from which he blows fire in an attempt to kill Bart and Milhouse on top of the effigy. Homer tries to save the boys by using a catapult to launch himself onto the effigy, but falls short and breaks its leg, destroying it. The other campers form a wall around Lassen and declare him to be shunned from the festival, while Bart and Milhouse escape safely.
Superintendent Chalmers and Principal Skinner fire Lassen from teaching at Springfield Elementary or any other school. Lassen then finds a new job as a prison guard. While ordering lights-out to the inmates, he encounters inmate Sideshow Bob. Discovering that they both murderously detest Bart Simpson, Lassen offers a partnership to kill Bart, which Bob nearly accepts. But when Lassen declares that they share the final kill, Bob rejects the deal.
Reception.
The episode received an audience of 6.70 million, making it the most watched show on Fox that night. 
Dennis Perkins of "The A.V. Club" gave the episode a B-, commenting that Lassen "fell flat" because Dafoe's reputation as a menacing actor comes from his physicality rather than his voice. He also observed that the series increasingly used Bart's misbehavior for jokes and plot development rather than emotional impact, but that this episode featured “classic Milhouse" moments in the episode, including urinating himself on Lassen's entrance and joining in with Lassen in bullying Nelson.