At South High School in Columbus, Ohio, students step outside in frigid weather and say 17 names, releasing a balloon for each one.

In Orange County, Fla., 17 empty desks sit in the Wekiva High School courtyard. Students sing — “Heal the world, make it a better place.”

In New York City, hundreds of students from LaGuardia High School walk into the street and sit in silence for 17 minutes.

Across the country, students are walking out of class for 17 minutes, one for each victim who died at the shooting in Parkland, Fla., exactly one month ago.

But the day of activism is not just limited to students stepping out of their schools. 

In Massachusetts, where more than a foot of snow fell on the state on Tuesday, students are preparing to rally at the statehouse and call for change.

Fifth-grade students in Akron, Ohio, who were studying the civil rights movement in class, are organizing a sidewalk protest, The Associated Press reports. At an elementary school in Virginia, students prepared a handwritten folder with information for the press.

In Silver Spring, Md., a long line of sign-holding students walk down a major street, with a police escort blocking traffic.

And outside the White House, protesters chant: “Hey hey, ho ho! The NRA has got to go!”

According to EMPOWER, the youth branch of the Women’s March, there are more than 2,850 school walkouts scheduled across the country, as NPR’s Adrienne St. Clair reports.

The national organizers called for a 17-minute walkout at 10 a.m. local time in every time zone.

But the actual details of the protest vary from school to school.

Some planned marches earlier in the day. Adrienne spoke to students at Centennial High School in Idaho who scheduled their walkout for 9:28 a.m., when the bell rings, rather than 10 a.m. “This will allow students to walk out in between classes, rather than getting up in the middle of a class,” Adrienne writes. “[Student body president Tommy] Munroe said some students may be too scared to leave if they are in a class with a teacher who doesn’t support the march, and so may not have an opportunity to participate.”

On the other hand, in Providence, R.I., student activists pushed the protest later, to 12:45 p.m., because “students aren’t allowed back into school once we walked out,” Dorbor Tarley explains on Facebook.

And some schools are going far beyond just a 17-minute walkout.

Students in some areas have organized marches, letter-writing campaigns and rallies with speakers, taking up part or all of the school day.

Various school districts also face different responses from administrators. Some have told students they won’t punish walkout participants. Others emphasize that normal school rules are still in place, and leaving class or campus without permission will result in disciplinary action.

Some administrators are promoting alternative forms of protest, like a moment of silence, or finding ways to incorporate the protest into a lesson plan.

Meanwhile, the ACLU is working to educate students about their rights. Schools can discipline students for walking out of class, even for a political protest, the group notes.

“But what they can’t do is discipline you more harshly because of the political nature of or the message behind your action,” the ACLU writes. “The exact punishment you could face will vary by your state, school district, and school. Find out more by reading the policies of your school and school district.”

Meanwhile, students in the Northeast are facing a challenge — the weather.

A northeaster dropped inches of snow on Tuesday, prompting some schools to close and disrupting walkout plans — although not always completely halting protests.