Principal Skinner and Mrs. Krabappel escort their students to the Fort Springfield Civil War site. But the trip is a dangerous one: the school bus is badly in need of repair and children nearly get sucked out of a hole in the vehicle’s floor. When the bus arrives at the destination, Skinner is aghast when he discovers that the fort now charges an admission fee. Due to a minuscule school budget, Skinner is unable to pay for the tickets. Instead, he instructs students to peer over the fort’s wall, where a recreation of a famous battle is in progress. Mrs. Krabappel warns Skinner that his penny-pinching has reached the breaking point and a teacher’s strike is imminent. Bart senses opportunity in the air and manipulates both parties, hoping to cause the school’s closure.

Bart’s efforts are successful and the teachers go on strike. Most of the students suddenly find plenty of free time on their hands-something they are not entirely used to. Lisa begins to experience withdrawal symptoms and acts nervous. Bart, used to the confines of school structure, also begins behaving in an odd fashion. Convinced that enough is enough, Marge sets out to reopen the school. A PTA meeting is organized in an attempt to end the teacher’s strike. But both sides refuse to resolve their differences. Left with little choice, the PTA uses ordinary citizens in place of teachers. After Bart dispatches a series of substitute teachers, Marge is called on to teach his class.

Bart’s fellow students single him out for punishment once Marge takes over the class. Unable to stand the merciless retaliation, Bart devises a strategy to reunite Skinner and Krabappel: he traps them in a room together and padlocks the door. Skinner and Krabappel realize they can lease cloakroom space at the school to house prisoners from overcrowded jails, thereby raising enough capital to give teacher’s a salary increase. The strike ends and school reopens.