FORT LAUDERDALE, Fla. — Early Thursday, dozens of bleary-eyed teenagers wearing matching maroon T-shirts gathered in an airport terminal here to head out of town, even though schoolwork was piling up at the end of the academic quarter.

The Floridians fretted about how cold it would be at their destination – one teen was chided for showing up in flip-flops. They hugged their parents goodbye and excitedly talked about their trip to Washington, a place many had visited before as tourists – but this time would be different.

About 200 students, teachers and chaperons from Marjory Stoneman Douglas High School – where a former student is accused of killing 17 people last month – and other schools in Broward County, Florida, flew to Washington, D.C., on Thursday to lobby legislators and participate in Saturday’s March for Our Lives. Organizers are expecting up to 500,000 participants in Washington. More than 800 marches are planned worldwide, according to the group Everytown for Gun Safety.

The students’ trip to the District was organized by Giffords, a gun-control group that is also bringing in students from Boston; Baltimore; Chicago; Irvington, New Jersey.; Omaha; New York City and Tucson, where then-Rep. Gabrielle Giffords, D-Ariz., was shot at a constituent event in 2011. The organization has arranged for injured students and family members of shooting victims to come to Washington on the private plane of New England Patriots owner Robert Kraft.

Robert Kraft

“Not only did their friends and teachers get shot and killed, other friends shot and injured .. most of them they had bullets flying over their heads,” said Mark Kelly, a retired astronaut and Navy veteran who founded Giffords with his wife. “This is not fair that they have to deal with something like this at their age. They wanted to go to Washington and be heard, and so I felt it was our obligation to help them.”

The students, who spent the week packing while juggling homework and school projects, said they are still grappling with trauma and survivor’s guilt. But in interviews they said sharing their stories and views was too important an opportunity not to take.

“I want to tell people, honestly, that they don’t know what we went through,” said Einav Cohen, a 15-year-old Stoneman Douglas student. “We’re the only ones who can explain how it was.”

Cohen said she can’t escape the shootings. She returns every day to the place where they happened. Students are pulled out of class for counseling, and school workloads have been lightened for the month so students are not overly stressed – something that will end with the start of the fourth quarter.

Cohen said she leans on her friends from school – the only other people who can fully understand what she is going through.

“It’s been difficult,” she said. “It’s been hard to go back to a normal routine.”

The specter of mass shootings can be hard to escape – the students flew out of the Fort Lauderdale airport, where five people were killed last year when a gunman opened fire in the baggage-claim area.

Florence Yared, 17, said she will keep the reason she is making the trip at the front of her mind – to honor the 17 people who were killed at her school. Yared said she once eschewed politics but has become politically active since the shooting. She hopes to start a dialogue with politicians who do not agree with her call for gun control.

“I kind of want to understand people’s opinions, why they think the way they do, and explain my point of view to help them understand why I think the way that I do,” she said.

Yared said she feels an obligation to push for gun control because she feels as though no one else is doing so right now.

“Even though we’re teenagers, we’re still American citizens,” she said.

Alondra Gittleson, 16, has lobbied lawmakers before – she was one of a group of Stoneman Douglas students who went to Tallahassee as the Florida legislature weighed, and ultimately voted down, an assault-weapons ban. The body ultimately passed a new set of gun regulations signed into law by Gov. Rick Scott, R, marking a major shift in a state known as a laboratory for gun rights.

“It was good when we talked to the state lawmakers,” Gittleson said. “Now we want to take it to the federal level. We all want to explain our stories.”

During the Feb. 14 shooting, she was hunkered down in the school’s auditorium.

“I feel survivor’s guilt sometimes. I wasn’t in that building. I didn’t experience the horrors they heard. I didn’t hear the gunshots,” she said. “I just remember the yelling, and the SWAT teams with their guns.”

Gittleson said she has spoken with therapists at school and is seeing a private therapist with her mother.

She said what also helps is being active in the #NeverAgain movement.

“After I went to Tallahassee, I kind of got some peace, I kind of calmed down,” she said. “I wanted to do something so badly, to speak to someone who could actually do something. Now we’re doing it again in Washington, and I really hope they listen to us and that it makes a difference.”

This is Gittleson’s first trip to Washington, and while she is ready to talk with lawmakers and join the march Saturday, she is less confident about the weather. She brought a quilted coat, something she doesn’t need often in Parkland.

“I hope it’s enough,” she said. “They’re saying it’s going to be really cold.”

One girl showed up to the airport in sandals.

“You brought other shoes, right?” said Debby Miller, the lead chaperon. “Listen to me – I’m such a mother.”

Miller is also a Broward County teacher. She reminded the students that they need to dress professionally when they visit the Capitol – no jeans – and that they need to stay cool if someone disagrees with them and keep their language appropriate.

Miller said the shooting at Stoneman had a powerful impact on her. She attended a rally at the courthouse in Fort Lauderdale three days after the shooting and was inspired by the students’ speeches. She volunteered to help with the bus trip to Tallahassee, and the trip to Washington.

“The day after it happened, I was standing in front of my class and I cried,” she said. “This is one of those moments where you have to choose whether you want to be on the right side of history or the wrong side. It’s a moral choice.”

She’s been impressed by the students, whom she describes as poised and mature in light of the tragedy they experienced. And while the trip’s itinerary has some leisure activities built into it – such as a trip to the National Museum of African American History and Culture – the main reason for it is never far from the students’ minds.

“The kids are super-excited,” Miller said. “They’re really determined. At the end of the day, they’re 15 and 16 years old, and they’re excited about all these opportunities, and their sad about all these opportunities, because of the reason they’re doing it.”

Zezima reported from Washington.