Students from more than 2,500 schools across the country will stream out of class Friday as part of a National School Walkout to demand action on gun reform.
The event held on April 20 also marks the anniversary of the 1999 Columbine High School massacre in Colorado, when a gunman killed 12 students and a teacher.
In the wake of the mass shooting at a Florida high school, many students -- including current Columbine students -- say not enough has been done to help prevent mass shootings.
During the walkout, which starts at 10 a.m. in each time zone, students will leave their classrooms and observe a moment of silence for shooting victims.
Other actions during the day will include marching to a local lawmaker's office, allowing open-mic time for students to share concerns and helping register those who are eligible to vote.
Lane Murdock, a 16-year-old sophomore from Ridgefield, Connecticut, launched the National School Walkout.
She was disturbed by her own reaction -- or lack thereof -- to the February massacre at Marjory Stoneman Douglas High School in Florida. The shooting left 17 students and faculty members dead.
"When I found out about the shooting at MSD, I remember I didn't have a huge reaction. And because of that, I knew I needed to change myself, and we needed to change this country," Lane said.
"We should be horrified, and we're not anymore. It's American culture."
Lane also said students should be empowered "to do the walkouts and become leaders in their communities, speaking up when they see inaction."
Push for legislation
The movement also encourages young people to push for legislation at the state level if Congress doesn't act.
"The federal government can set standards and practices that apply to all states around gun safety. But states have the option of passing additional measures to protect their own residents from gun violence," the website says.
Students are calling for several measures, including banning assault weapons, high-capacity magazines and bump stocks; mandating universal background checks; placing a minimum age of 21 on all gun purchases; implementing waiting periods between a gun purchase and gun transfers and allowing families to petition a court to remove guns from individuals at risk of injuring themselves.
While there hasn't been major congressional action since the Parkland massacre, some cities and states have toughened gun control.
In Florida, after Parkland students rallied at the state Capitol, Republican Gov. Rick Scott signed a gun bill called the Marjory Stoneman Douglas High School Public Safety Act. It raises the minimum age to buy any firearm in Florida to 21, bans the sale or possession of bump fire stocks and adds $69 million in funding for mental health services in schools.
In Vermont, Republican Gov. Phil Scott banned bump stocks, limited the size of magazines, expanded background checks for gun purchases and raised the minimum age to purchase firearms to 21.