Dave is a bright, highly talkative fifth grader at Laketon Elementary School. After researching Mahatma Gandhi for a social studies project, he attempts to practice a day of complete silence to order his mind. His low tolerance for the girls in his grade leads him to challenge them to a silent contest, aiming to prove that boys talk less than girls.

Lynsey is an intelligent and talkative fifth-grade girl who strongly dislikes the boys in her class. She accepts Dave's dare to be silent, organizing her friends into a dedicated, tightly disciplined team. As she stops speaking aloud, she discovers a preference for thinking carefully before expressing herself.

Abigail Hiatt is the demanding, efficient administrator of Laketon Elementary. She prefers strict order and struggles to manage the notoriously loud fifth-grade class, whom the staff calls the "Unshushables." She views the students' sudden refusal to speak as a direct threat to her authority rather than a positive behavioral shift.

Mr. Burton teaches English and language arts at Laketon Elementary. Instead of punishing the silent students, he finds their new communication style fascinating. He begins taking detailed notes on their behavior, planning to use the no-talking contest as the basis for a scholarly paper in his master's degree program.

The science teacher at Laketon Elementary. She uses her scientific mindset to observe the children and tests their speaking rules through classroom experiments. While intrigued by the silence, she worries about the potential for anarchy.

A social studies teacher at Laketon Elementary who focuses heavily on rules and procedures. She resents the students' game and supports administrative efforts to suppress it, preferring traditional classroom management over experimental learning.

The music teacher at Laketon Elementary. When her students refuse to sing properly, she assumes they are protesting something and adapts her lesson by having them hum and clap rhythms instead.

The physical education teacher. She enjoys the calm atmosphere created by the students' silence and quickly adopts their hand gestures to manage her gym classes.

A math teacher who initially tries to force the students to speak normally. She soon realizes that despite their short verbal answers, the students are deeply engaged in learning fractions and decimals.

A teacher at Laketon Elementary. She produces an intercepted note during a staff meeting, providing the school administration with the written rules of the students' secret game.

A top science student in the fifth grade. She strictly adheres to the contest rules both in class and at her extracurricular flute lesson, where she answers her instructor by tapping on a music stand.

A fifth-grade boy in Mr. Burton's language arts class. He helps facilitate communication between the rival team leaders but teases Dave for willingly interacting with a girl.

A fifth-grade boy who participates fully in the game. He refuses to shout out the traditional yells during his after-school karate class, confusing his instructor.

A fifth-grade boy who prioritizes the contest over his personal appearance. He allows his barber to cut his hair far too short rather than break his vow of silence to complain.

A grumpy local barber. He requires his young clients to speak up and complain loudly, or else he cuts their hair excessively short.

A fifth-grade boy whom Principal Hiatt uses to try and force Dave to break the silence rule. When Dave rebels, Todd initiates the applause that spreads throughout the cafeteria.