It has been a year since Kaitlin Roig barricaded herself and 15 first-graders in a bathroom at Sandy Hook Elementary School, hiding from a gunman who would go on to kill 26 people in an 11-minute rampage.

Roig doesn’t know if Adam Lanza, the 20-year-old shooter, ever entered her classroom in Newtown, although she could hear gunfire and terrified pleas from the hallway and adjacent first-grade classroom.

“For myself, I am so aware that roles could have so easily been reversed,” said Roig, 30, who has since married and now uses the name Roig-DeBellis.

“I remember, in the days after, it was so hard to get out of bed,” she said, sitting on a sofa in her Greenwich home. “I just walked around singing Amazing Grace just over and over and over, because it was just so incredibly hard.”

The Dec. 14 tragedy at Sandy Hook, among the most deadly school shootings in U.S. history, rocked the suburban town 70 miles northeast of New York City.

Lanza, a loner who appears to have had severe emotional problems, used guns that were legally purchased by his mother, Nancy Lanza. He killed her in her bed, then drove to the elementary school he had once attended, shooting his way in just as the school da began. After the rampage, he shot himself.

As the nation marks the anniversary of the massacre, Newtown has asked the public to stay away.

For her part, Roig-DeBellis has planned a trip — a spa visit and maybe a nice dinner — anything to turn her focus away from the terror and excruciating sadness of that day.

The offices of Sandy Hook Promise, a parents group founded in the weeks after the shootings, are in downtown Newtown. Artwork sent by children from across the country has been framed and mounted on the walls there. Scattered on tables are pamphlets on foundations set up by the families.

Seated at one of those tables, Mark Barden, who lost his son, Daniel, gives a long pause when asked about forgiveness.

“I’m trying to approach every bit of this with an open heart and an open mind,” Barden said. “It’s a work in progress.”

Like many other Sandy Hook parents, Barden has kept up a punishing schedule over the past year, traveling to Washington to meet with lawmakers to support a gun law that stalled in the Senate, and promoting the work of Sandy Hook Promise.

“Maybe it has saved me,” he said of the group. “The way that Daniel lived his short life, I know that he would have done a whole lot of good. We take it very seriously now that it’s our responsibility to do that good work.”

For Barden, a guitarist who often performs in town, every day is an anniversary. The last haircut. The last swim team practice. The last Thanksgiving.

“A lot of the memories are happy. But we’re still so new at this. It’s still so early on that it’s hard not to get caught up in the grief,” he said.

The parents of the children who died that day talk often about their struggle to break through the feeling of helplessness. Parent Together, an effort Sandy Hook Promise launched in November, aims to show people, regardless of their politics, that gun violence can be prevented.

“Nobody’s pro gun violence. So, it’s not like there’s two sides to this,” Barden said.

Roig-DeBellis ended up taking more than a year off from teaching and has devoted that time to Classes4Classes, a charity that facilitates acts of kindness between groups of students across the country. She plans to return to teaching this summer.

“What happened that day has nothing to do with being a teacher,” she said.