It was less than a week into her job as principal and Lisa Siegman was already confronted with her first major crisis.

As a first-year principal on the morning of Sept. 11, 2001, Siegman was just a few hours into her third day on the job when two hijacked commercial planes struck the World Trade Center less than two miles away. Siegman’s school, P.S. 3 in the West Village, was immediately converted from a place of learning into a refugee shelter.

“It just turned into survival mode,” recalled Siegman.

Within hours, hundreds of students who had evacuated from schools near ground zero were pouring into P.S. 3’s nearly century-old building on Hudson Street. Some of those schools would not reopen for months, causing their students to temporarily become P.S. 3’s.

Siegman, who is still principal at P.S. 3, one of the top-performing schools in the city, said she remembers few details from that day other than how quickly her responsibilities as a school leader had changed and how urgently her skills were needed.

Parent phone calls needed to be made, but most phone lines were down. Information had to be disseminated to staff and parents, but initial announcements from the Department of Education was unclear and conflicting.

“It was this huge logistical problem,” Siegman said. “Suddenly I had to worry about this whole new set of challenges.”

As the city prepares to commemorate the tenth anniversary of the Sept. 11, 2001, attacks on Sunday, new attention is being given to the largely unheralded success of educators across the five boroughs that day in coordinating evacuations and dismissals for more than 1 million students.

A new documentary film, produced by the United Federation of Teachers, compiles interviews from dozens of those educators to offer a glimpse into how the crisis was managed from inside the schools and celebrates their roles in shepherding more than 1 million students to safety.

“Not a single child was lost. Every single child got out safely,” former UFT President Randi Weingarten said last night at a screening of the film. Other speakers included police commissioner Ray Kelly, who personally thanked teachers — before hurrying off to deal with a current terror threat — and Harold Levy, the schoolschancellor at the time.

A teacher in Brooklyn 10 years ago, current UFT President Michael Mulgrew recalled last night how his classroom became a makeshift news hub on Sept. 11 because it was the only one equipped for audio and video. He was in the middle of teaching a class when teachers came in to watch the news and everyone saw together the second plane hit the World Trade Center.

“Anyone who was in a school that day remembers that day,” Mulgrew told GothamSchools earlier this week. “There were no directions or anything that day.”

Even then-Mayor Rudy Giuliani, who is largely credited for his heady management of the crisis, didn’t know what to do, Levy and Weingarten revealed in a previously untold story last night. Giuliani’s first instinct was to allow schools to dismiss children without parental consent. But after fierce protests from a united Levy and Weingarten, Giuliani relented and allowed principals to keep children in the schools.

For the teachers and principals who lived through that day and remain in the school system, revisiting the experience in the classroom will be especially difficult. To help, earlier this month Chancellor Dennis Walcott released lesson plans and curriculum material that can be used to help children with no memory of the attacks learn about its significance during the 10th anniversary year.

But at P.S. 3, an elementary school, most students weren’t even born yet and Siegman said she had no plans to draw specific attention to the event in the coming weeks.

Standing in the converted gym on the bottom floor at P.S. 3, where 10 years earlier hundreds of evacuees had spent hours playing hula hoop and other games while they waited to be picked up by parents, Siegman rejected the notion that her role was in any way heroic. To her, being principal of a school transcends any crisis that might take place under her roof.

“This place was where my focus was,” Siegman said. “These kids were where my focus was.”