Squidward is disdainfully watching Squilliam play his clarinet at a concert. When Squilliam finishes, Squidward leaves. He also hears someone say "He's so good, he doesn't even have to play to be good!" As Squidward walks out of the recital hall, he is mistaken for Squilliam and is then offered to teach a music class, to which he accepts.
Later, he comes to the music class wearing a wig, posing as Squilliam. He prepares his desk, and a kid asks him if he is going to write his name on the board "like most professors do." Annoyed, Squidward tells the kid to write his name on the board. Shortly after that, Squidward discovers that SpongeBob and Patrick are in the music class he is teaching, which annoys him even more. SpongeBob and Patrick are then told that they are allowed to stay just as long as they behave themselves and keep quiet about Squidward's real name. Squidward starts teaching, but is interrupted by SpongeBob's laughter. When asked about it, SpongeBob claims that Patrick was tickling his foot, but shortly after reveals that he was tickling his own foot. In order to avoid any more distractions, Squidward moves SpongeBob away from Patrick, but he keeps on laughing anyway. When SpongeBob is told to stop tickling his foot, Patrick reveals that it really was him that time, much to Squidward's surprise.
Squidward starts teaching about musical scales by drawing lines on the chalkboard. Patrick then explains how they remind him of a railroad track he saw at a railroad convention last week, where he bought himself a conductor's hat. Soon after, he starts riding a mini train, only to get trapped in the trash can, though he comes back inside a minute later.
Then, Squidward starts teaching the class about metronomes, much to the interest of SpongeBob and Patrick (though SpongeBob mistook it for a garden gnome). They start making a ticking noise and a news reporter suddenly comes in, wanting to do an interview with "Squilliam Fancyson," although he is soon more interested in SpongeBob and Patrick and how they are in a trance. Squidward then angrily kicks him out after talking about possible paranormal activity. SpongeBob and Patrick stop ticking and exit their trance when the bell rings. They forget where they are and start calling Squidward by his real name, which upsets the rest of the class, causing them to leave. Squidward desperately blocks the door with his body to no avail, as the police come in along with the news reporter, the real music teacher, and Squilliam Fancyson himself. After noticing that Squidward does not have a unibrow, he is quickly arrested for "impersonating a genius," leaving SpongeBob and Patrick alone with the metronome ticking. Soon after, they are in a trance again, imitating the metronome as the episode ends.
The real name for "impersonating someone" is called "identity theft."
The plot of this episode is somewhat similar to the plot of "Artist Unknown" (Squidward teaches a class, to which, SpongeBob happens to apply). This time, SpongeBob is not the only student in his class and Patrick appears as well.
Patrick claims he wanted to learn to play an instrument, but he already knows how to play an instrument, which is the drums. However, due to his stupidity, he may have forgotten.
At the beginning, Squidward was wearing the same sweater that he wore in "Snowball Effect."
This episode takes place after Band Geeks and/or Squilliam Returns because in the former episode, Squidward refers to Squilliam as, "Squilliam Fancyson from band class" and in the latter, Squidward refers to Squilliam as, "...my arch rival from high school, Squilliam Fancyson," suggesting that they had not talked since then.
When the fish said he was commuting from upstate, it could possibly be a reference to Tom Kenny's hometown, Syracuse, New York, which is one of Upstate New York's major cities.
After being hypnotized, SpongeBob and Patrick recite a line from the 1976 film Taxi Driver.
When Patrick rides into the trash, Squidward exits the building, and places the can outside. Later, when both the police and the news crew come into Squidward's classroom, they enter the same door that once led to the outside, but instead, it lead into a hallway.
Although it was established in older episodes that Squidward's middle initial is J, in this episode, however, Squidward says it is Q. It is unknown which one is correct.