It started out last month as a writing exercise on the 1963 Birmingham Children’s Crusade, when more than 1,000 students skipped school and marched to demand civil rights. Then the class assignment mushroomed into a plan — hatched by 10- and 11-year-olds — to stage a little civil disobedience of their own.

So Wednesday, the students in Craig Sampsell’s fifth-grade class at Case Elementary School in Akron, Ohio, will pick up posters they drew and walk out of their classrooms, joining many thousands of other students in a nationwide protest against gun violence after the killing of 17 people in a Florida high school last month.

Asked whether that was an appropriate age to be protesting about a disturbing event, Principal Danjile Henderson said: “My fifth-grade students were very aware of the details of the events and wanted to have their own peaceful protest.”

Still, she drew lines around who could participate and how. Third- through fifth-graders may walk out; second-graders can observe the protest, but not walk; kindergartners and first-grade students will remain in their classrooms for discussions on school safety in general that avoid the shooting itself.

With some parents wanting their children to get firsthand exposure to a nationwide political demonstration; others worried that the protests are stoking the fears of young children about a threat that remains uncommon; and still others objecting to the gun-control message entirely, one question has been weighing heavily on school administrators: How young is too young for children to join the walkout?

Many districts and schools that are tolerating, if not encouraging, participation in what organizers call the National School Walkout are also calibrating their approach for their youngest students. In New York City, middle and high school students may walk out of class with approval from a parent, but elementary school students cannot leave unless a parent checks them out.

At Woods Cross Elementary School in Woods Cross, Utah, students will be allowed to leave class at 10 a.m. and go to the gym for 17 minutes, the same starting time and duration (one minute for every victim in Parkland, Fla.) as other walkouts.

“We’re giving them an opportunity to express their First Amendment rights in a safe place,” said Rachel Peterson, a teacher who is also safety commissioner for the state board of the Utah PTA.

In suburban Nashville, David L. Snowden, director of schools for the Franklin Special School District, sent an e-mail to families saying that students in its elementary schools, which run through fourth grade, would not be allowed to participate in the walkout, but that students in grades five and up could join.

He said he was concerned that very young children would not understand what it was about. “Just to walk out of class for 17 minutes, I’m not sure what that is really teaching.”

Some districts, generally in conservative areas, are trying to discourage any type of school walkout, warning that any student who participates will be marked as absent.

Even some schools where demonstrations are being allowed are being careful about the tone. Joel Pelcyger, head and founder of the PS1 Pluralistic School in Santa Monica, Calif., consulted with parents before deciding that the walkout was not a political statement, but a way to empower his students.

“The way you make people safe is by feeling that they’re part of something larger than themselves,” he said.