More than 40 schools in Philadelphia and South Jersey have students planning to walk out of class Wednesday to protest mass shootings like the Parkland, Fla., tragedy. Not all of the schools are supporting their students in this action. But they should.

It's a shame when children feel compelled to speak up because adults have failed them, but sometimes that's the only way to ignite groundbreaking change. Think of the children's marches in Birmingham, Ala., organized by the Rev. Martin Luther King Jr., which brought the national attention he needed to fight segregation in the 1960s.

The Valentine's Day slaying of 14 children and three adults by an apparently deranged former student at Marjory Stoneman Douglas High School should have brought immediate and dramatic changes in America's gun laws. Instead, Congress and President Trump have discussed a variety of meager reforms without passing anything.

No one should be surprised. If the 2012 massacre of 20 children and six adults at Sandy Hook Elementary School in Newtown, Conn., couldn't shake Congress out of its NRA-induced lethargy to pass stronger gun laws, perhaps nothing will. Not even another preventable travesty like Parkland.

So, students are taking matters in their own hands, as best they can since most aren't old enough to vote the lawmakers sitting on their hands out of office. The 17-minute walkout, first proposed by two high school girls in Brooklyn, N.Y., will be their way of saying they have had enough. Adults need to do more than listen to their protest; they need to act.

Their first action should be to follow the lead of Philadelphia Superintendent William R. Hite Jr. and make clear that no disciplinary action will be taken against students who walk out. "This can be a learning opportunity that helps our students apply lessons that they are learning in school," said Hite in a letter to parents and guardians.

He also stressed that students participating in the demonstration should be respectful of students who don't. That's a very important point, especially in Philadelphia, where daily gun violence takes a huge toll without getting anything close to the attention that Parkland has received.

"When something happens in the white community, the black community is expected to support them," Tatiana Amaya, a Mastery Charter School student told an Inquirer reporter. "The focus isn't 'What can we do to make black and brown kids feel safe in school?'"

She's right; not enough attention is paid to the murders that touch the many more children and their families who live in neighborhoods held hostage to gun violence. But the walkout Wednesday isn't the culmination of the battle to get tougher gun laws; it's another beginning. And, unfortunately, many more beginnings may be needed before significant change occurs.

That's OK. The children who marched and went to jail in Birmingham didn't see significant change for years. But when change came, they knew they had played a role in achieving it.

So, too, will the students who walk out in protest Wednesday, if lawmakers in state legislatures across the country and Congress finally take some common-sense steps to reduce the too-easy access that allows mass murderers to get their hands on high-powered, rapid-fire weapons.