"Wayside School is Falling Down" focuses on the wacky adventures of the 29 children in Mrs. Jewls' 30th-story class. This children's book, written by Louis Sachar in 1989, is a sequel to "Sideways Stories From Wayside School."
The book has 30 chapters and begins in Mrs. Jewls' classroom where she receives a package containing a computer. Teaching a lesson on gravity, she drops the computer out the window.
A new student is introduced to the classroom: Benjamin Nushmutt. Embarrassed by his name, Benjamin tells his classmates that his name is Mark Miller. Bebe writes mean notes about Mrs. Jewls, which she then says her younger brother wrote, even though she does not have a little brother. Mac continually disrupts the class with wild stories that eventually leads Mrs. Jewls to assign the class more homework.
During show and tell, Shari brings a hobo to the classroom whose story about winning a spelling bee while not wearing any socks encourages a "no-socks" superstition among the students before their next spelling test. Paul becomes obsessed with the urge to pull Leslie's pigtails. When Paul falls out the window in the classroom, the only way to save him is for Leslie to offer up her pigtails as a rope.
Myron wanders into the school basement in an effort to quench his desire for freedom. There, he meets some men who give him a choice: be safe or be free. He chooses to be free, and returns to Mrs. Jewls' classroom. A toy dog that can keep Todd out of trouble but that also can transform into a wolf chomps off student Joy's finger when she attempts to use the toy to her advantage. For 18 straight days, the lunch special is Mushroom Surprise; when Ron eats it, it makes him temporarily fall in love with DeeDee.
Benjamin starts to consider telling the other students his real identity, but he decides his alias of Mark Miller is superior. After complaints from the other teachers about the loudness of their music class, Mrs. Jewls encourages the students to play even louder. DJ loses his watch and is distraught, but Kathy makes him feel even worse. When the watch is found, DJ gives the watch to Kathy because he believed her taunting to be comforting. Kathy sings to the tune of "London Bridge Is Falling Down," replacing the words to include Wayside School.
Jason cannot stop chewing pencils until Mrs. Jewls tapes his mouth shut. Joe and John tease Dana because of her emotional responses to stories about animals, while Mrs. Jewls finds Dana's emotions to be endearing. Calvin decides to get a potato tattoo on his ankle. Former 30th-floor teacher Mrs. Gorf seems to be haunting the students. They dismiss the idea of her without seeing a set of footprints near the monkey bars that are too large to be a student's. Dameon denies being in love with Mrs. Jewls and leaves a dead rat in her desk.
Miss Franklin, a substitute teacher, shows up to the classroom and the students plan to play pranks on her. Benjamin again decides it is time to come out with his real name, which leads the class to tell Miss Franklin that they are named Benjamin, too. Miss Franklin reveals that her name is Benjamin.
Allison believes their classroom in on the 29th floor because Miss Zarves' classroom on the 19th floor does not exist. She is later welcomed into Miss Zarves' class, where she meets the other students who have all forgotten about their past. They do not care, because Miss Zarves always gives As, and Allison begins to slowly forget her origins as well. She soon realizes that Miss Zarves assigns a lot of work to make the students not think. She begins trying to annoy Miss Zarves and soon finds herself out of the class, wondering if she was actually in the classroom or in a dream.
Mr. Kidswatter finds a card with an insulting comment about himself signed by someone named Eric. He suspects the three Erics in Mrs. Jewls' class but is unable to discover who wrote the card. Joe orders potato salad from Miss Mush, which he and John mold into the shape of Mrs. Gorf's face. The face comes alive and they must eat it to get rid of her again.
Benjamin decides once again to tell everyone his name. He is afraid of being thought of as weird, until his classmates recount their own stories from the school. In the final chapter, a storm causes panic in the classroom. Mrs. Jewls rings a cowbell and the wind carries the sound. Soon, the students and teachers find the school filled with cows that were attracted to the sound of the cowbell. The school is closed down temporarily, and all of the students are sent to other schools.