SHANKSVILLE, Pa. - Crystal Muia, a middle-school math teacher from West Virginia, was surprised two years ago when she showed students photos of her visit to the memorial site here.
None knew about Flight 93.
"They'd never heard it," Muia said.
On Wednesday, the teacher and her students trekked the three hours from Charles Town, joining hundreds of others to mark the 9/11 anniversary on the site of what is generally considered terrorism's first battlefield.
As the years pass, the numbers of attendees paying tribute each Sept. 11 to the 40 passengers and crew members who died here, when a hijacked aircraft crashed during an attempt by passengers to retake control, has dwindled. So, much of the day's message was directed to the next generation.
Few who were babies or toddlers on 9/11 can remember the day. Many haven't learned about it - or much about it - in the years since.
"When I told someone at school I was going to a 9/11 event, they said, 'Are you going to New York?' " said 14-year-old Hannah Neal, one of the students from Charles Town. "People have forgotten Pennsylvania."
As she and others gathered under cotton ball clouds, Interior Secretary Sally Jewell pledged that the National Park Service would faithfully protect the site and preserve the memory of United Airlines Flight 93.
Jewell said she had been overwhelmed with emotion the night before at the crash site. While lighting luminaria at the marble "Wall of Names" that commemorates each passenger and crew member, she said, she saw a contrail stream across the sky.
"We are in the forever business," Jewell said, wiping away tears. "We will make sure future generations know the story."
Two large bells tolled as the names of the passengers and crew whose actions likely saved the Capitol were read, ending at 10:03, the moment the Boeing 767 slammed into the old strip mine in 2001.
The West Virginia students weren't just observers. Each wore a T-shirt sold to help raise money for the monument.
Hannah and Jillian Sobrino, also 14, led a campaign that raised $2,000 by selling shirts with the names of the passengers and crew, and encouraging friends to make donations in 93-cent increments.
As part of her efforts to educate children about the attacks and their importance, Muia last year arranged for David Beamer, father of Flight 93 passenger Todd Beamer, to speak at Charles Town Middle School.
Todd Beamer's "Let's Roll" was the rallying cry that ended with his fellow passengers trying to gain access to the cabin.
In his talk to the students, Beamer "focused positively on the 40 as heroes and how children can be heroes in their own way, in their own lives," Muia said. "We're trying to build character and it's all about the negative in today's world."
The crowd remained seated at the end of the ceremony as the a cappella chorus of the U.S. Navy Band Sea Chanters sang "You Raise Me Up" and Flight 93 family members - some moving more slowly than in years past - filed out through an opening in the "Wall of Names" and into a field.
The figures disappeared in the thick growth of black-eyed susans, planted as part of the project to reclaim the battered landscape several years ago.
They were headed to the large boulder that marks the site of the plane's impact and the victims' final resting place - to say their goodbyes, until next year.