Benjamin Nushmutt and Mark Miller
Benjamin is a new student in Mrs. Jewls' classroom whom everyone thinks is named Mark Miller. As a new student, Benjamin is naturally a little timid among strangers and makes no effort to clear away the confusion by telling everyone he is not Mark Miller. He is also reticent because he is ashamed of his funny last name.
Benjamin does eventually try to tell everyone Mark Miller is not his name, but every time he tries, a distraction keeps him from doing so. At one point, a substitute takes over the class from Mrs. Jewls and the students decide to pull pranks on her. When Benjamin finally does succeed in telling everyone his real name, they all think it is Mark Miller pulling a prank.
Benjamin finally does succeed in telling everyone he is not really Mark Miller. This revelation also clears confusion about an unclaimed lunch on Mrs. Jewls' desk. Eventually, the name confusion also clears up a case of mistaken identity involving a girl named Allison.
Miss Zarves and Allison
Allison's confusion about the identity of Mark Miller stems from her being inducted into the strange class of Miss Zarves. Miss Zarves teaches in the classroom on the nineteenth floor of Wayside School. Due to a construction mistake, however, the numbering system left out number nineteen so technically there really is no nineteenth floor official.
Miss Zarves, in other words, is the non-existent teacher in a non-existent classroom on a non-existent floor. Allison soon discovers that this strangeness is reflected in the makeup of the classroom. Miss Zarves' class include a teenage boy, an adult woman, and a younger boy.
Allison concludes that Miss Zarves has chosen to deal with the fact that she and her classroom do not technically exist by making attendance on the nineteenth floor an exercise in utter futility. Mark Miller—who really does not exist and is actually Benjamin Nushmutt—gets Alison to wonder if the classroom on the nineteenth floor might actually be Hell. Allison finally does escape but Miss Zarves continues to give all her students good grades no matter what kind of work they turn in.
Hobo Bob
Bob is a hobo who is brought in for show-and-tell by a student named Sharie. His appearance is that of a typical hobo: scraggly beard, dirty clothes, patches on his pants. During the course of a question and answer with the students Hobo Bob reveals he does not take baths. When he needs to wash, he simply walks around in the rain.
One student asks Hobo Bob why he is not wearing socks. His reply is that he does not believe in socks. When asked why he is a hobo and does not have a job, he explains that nobody will hire him because he never wears socks.
Finally, Allison asks him why he can't just give in and wear socks even though he doesn't believe in them. This finally causes Hobo Bob to explode over the obsessive interest in the students about his lack of socks. He finally explains that Albert Einstein never wore socks and also never had to deal with questions about why he didn't wear socks. When show-and-tell finally ends and Hobo Bob leaves, all the students proceed to remove their socks.
