Ida is a 14-year-old eighth-grade student living in the rural farming community of Elk Valley, Colorado. Less than five feet tall, she operates her family's Model T car by steering while her brother pushes the pedals. She dreams of moving beyond her farming life to attend high school in Steamboat Springs and become a teacher. When the local school closes unexpectedly, she attempts to teach the remaining semester in secret while managing heavy farm chores.

Tom is a 14-year-old eighth grader and Ida's closest companion. He comes from a tidy farm owned by his German immigrant parents. Mechanically minded, Tom builds his own crystal radio from a cardboard tube and copper wiring. He aspires to become an electrical engineer and devises the plan for Ida to become the substitute schoolteacher so they can both take their high school exit exams.

Herbert is an older student at the Elk Valley school who frequently misses classes to assist his widowed father with farm labor. He projects a tough attitude to mask his academic insecurities and his fear of falling behind his peers. He tests boundaries immediately by refusing to participate on the first day of the secret semester.

Mr. Jordan is the portly owner of the local feed-and-grocery store and the chairman of the school board. He possesses a deeply conservative view of rural life. He believes education is largely unnecessary for farmers and entirely wasted on girls. He prioritizes saving the community money over providing academic opportunities for its youth by quickly canceling the school session.

Miss Sedgewick is a tall county school inspector operating out of the Steamboat Springs Education Office. She holds the authority to administer the eighth-grade exit exams necessary for high school admission. She assesses rural schoolhouses carefully and maintains high standards for academic orderliness.

Mrs. Bidson is a hardworking farm woman who raises three children in Elk Valley. Though she lacks a formal education herself, she strongly supports her daughter's academic aspirations. She provides steady encouragement and practical advice as Ida manages the heavy burdens of teaching and farm labor.

Mr. Bidson is a dedicated farmer working hard to maintain his family's livelihood in the valley. He supports Ida's ambitions as long as they do not interfere with her necessary agricultural duties. He treats his daughter with maturity and requires her to take responsibility for her own choices.

Mr. Bixler is a struggling widower managing a decrepit sheep farm that recently suffered heavy livestock losses. Embittered by financial hardship, he views the local school strictly as a drain on the labor he desperately needs from his son. He aggressively opposes any attempts by educators to pull his boy away from his chores.

Miss Fletcher is a small, dark-haired teacher who oversees grades one through eight in the Elk Valley one-room schoolhouse. An unmarried woman wholly dedicated to her profession, she earns a minimal salary to provide the community's primary education. A family medical emergency forces her to abandon her post.

Felix is Ida's seven-year-old brother and a primary-grade student at the Elk Valley school. He relies on his older sister for transportation to classes. He regularly assists with the schoolhouse upkeep by carrying in wood for the iron stove.

Mary is Tom's younger sister and an early-grade student at the local schoolhouse. She participates in the covert academic plan and practices her primer readings alongside the other young children.

Natasha is a 13-year-old student known as the best speller in the Elk Valley classroom. She eagerly participates in the schoolhouse routines. She occasionally assists her slower classmates with their math lessons.

Charley is a young student in the Elk Valley schoolhouse. He diligently practices parsing sentences and depends on the older students for academic guidance during the spring semester.

Susie is a young student who possesses a beautiful singing voice. She maintains classroom traditions by stepping forward to lead her peers in morning songs.

Mr. Hawkins is a local Methodist minister residing in the farming community. He acts as a moral voice for the valley's residents by openly advocating for the children's right to continue their education.

Shelby is the toddler brother of Ida and Felix. He requires constant care and supervision from his family members, adding to the daily household chores Ida must manage.