In an interview, Dr. Snowden said he was not concerned that very young children would be frightened by the walkout, only that they would not understand what it was about. “Sometimes I think when you’re teaching children, especially younger children, you try to take into consideration, will there be a full understanding of what they’re doing and why they’re doing it,” he said. “Just to walk out of class for 17 minutes, I’m not sure what that is really teaching.”

Even within Akron’s 50-school district, agendas for Wednesday differed markedly from school to school. At Firestone Park Elementary, students were expected to read a poem about peace. At Pfeiffer Elementary, students would be reviewing safety procedures. And at Robinson Community Learning Center there were no plans at all — students had not expressed an interest, according to the district.

Elise Cappella, a clinical psychologist and associate professor at New York University’s Steinhardt School, said there was a difference between what the youngest students — from kindergarten to second grade — and older children could understand. While not advocating any particular stance, she said: “Schools could make the decision that kids in kindergarten through second grade are not provided the opportunity to walk out. They are cognitively, socially, emotionally younger. They may feel more fear about it and less understanding.”

Children in the third grade and up, she said, will be more likely to be exposed to news and hear their parents talking about it. “They are reaching a point where having something that’s potentially positive and productive to do that makes them feel a sense of agency and safety could be a good thing,” she said.

Ms. Cappella said that whether elementary schools decided to participate in the protest or not, the goal should be to project a sense of community to their students. “And if you can create that space,” she said, “whether that’s in the classroom or in the hallways or in the schoolyard or out at a protest or a march, that’s the most beneficial space for young kids to be in.”

Some school districts are trying to discourage any type of school walkout, regardless of age, warning that any student who participates will be marked as absent from class or even disciplined.