Seven years after terrorists struck in New York, Washington and rural Pennsylvania, there is no consensus in the educational community on what or how to teach students about the attacks, or even whether Sept. 11 should be mentioned at all.

Neither Pennsylvania nor New Jersey mandates teaching or observing 9/11. Officials in both states say the matter is best left to school districts.

As a result, for some schools Sept. 11 means flag-waving and patriotic assemblies. Others mark the anniversary with a moment of silence. Some treat it as a history lesson, asking students to read, write, think and speak about a national tragedy.

And some treat the day like any other.

Former New Jersey Gov. Tom Kean, who chaired the national 9/11 Commission, said 9/11 should be woven into every school district's curriculum.

"If it's not taught properly, it could be pretty scary," Kean said. "Older kids will remember it, and younger kids will hear about it. It's a wonderful teaching tool."

Nationally, teaching about 9/11 "really depends on the school," said Chris Bradshaw, a vice president at the American Institute for History Education, a nonprofit in New Jersey. "Some don't touch it at all. They say, 'That's the parent's responsibility.' But in the upper levels, it's finding its way into the curriculum a lot more."

That's where Bob Barnshaw stands. Barnshaw, a history teacher at Washington Township High in Gloucester County, this summer attended a conference where Kean reminded educators of their responsibility to teach about the attacks.

Teaching an event so new it is not mentioned in some textbooks is both a challenge and a matter of great interest to Barnshaw.

Fitting Sept. 11 into the curriculum is tough, he said: While the date falls at the beginning of the school year, recent history is taught at the end of the school year. Also, "you don't really know the kids yet, so it's hard to gauge the emotional impact it will have," he said.

But Barnshaw said he hoped schools went beyond simple ceremonies and used the anniversary to spark meaningful learning.

"It's so uniquely impactful," he said. "It should be given its own pedestal."

In his classes, Barnshaw asks students where they were on the day, what they remember. He tells them what it was like at the high school, then reads excerpts from a scrapbook with writings from students he took to the twin towers site in 2002.

Finally, he connects the events to what's going on in Afghanistan and Iraq and what could happen in Iran.

"What I don't do, and I don't recommend anyone do, is just show clips of planes hitting buildings," he said.

Later in the school year, Barnshaw's U.S. History 2 classes explore the subject in greater depth in a unit on the origins of al-Qaeda and how the attacks were carried out.

There's a key difference, however, between learning about 9/11 as a major event in U.S. history and simply marking the day. Most schools at least do the later.

In Collingswood, Superintendent Scott Oswald said, there is no district initiative, but instead a request for each school to handle the day in an age-appropriate way.

"As was the case on Sept. 11, 2002, normalcy is important for students, particularly the youngest ones," Oswald wrote in an e-mail.

The Philadelphia School District provides curriculum support but lets schools decide what to do.

In the Souderton Area School District today, Indian Crest Junior High will fly a flag bearing the names of all who died in the attacks. Faculty will wear commemorative buttons, and eighth graders will watch the documentary Through a Child's Eyes: September 11th, 2001.

In the Delsea Regional School District in Gloucester County, students will observe a moment of silence, and teachers have been asked to talk about the event.

"We don't have the same level of activity surrounding this sad day as in the past," said Frank Borelli, Delsea superintendent.

Some use the day as a way to talk about patriotism, an option popular at lower grades. At Fountain Woods Elementary in Burlington Township, principal John Johnson leads the school in a celebration of "the things that the events of 9/11 revealed about the strength of our nation."

Johnson speaks to students about the attacks, then each class marches outside, waving flags and planting them in the ground. Local emergency-services personnel are invited.

Johnson does not dwell on the deaths. Instead, his students - some not born until after the attacks - think about heroes.

"I have to be very careful," Johnson said. "There are some parents who are very guarded about what they say to their children."

At Chestnutwold Elementary in Haverford, principal Tim Bickhart and a guidance counselor organize a 20-minute ceremony.

"We do not want to frighten the students nor focus on the thousands of lives lost," Bickhart told his staff in a memo. Students read a poem, sing patriotic songs, and observe a moment of silence.

At Sharp Elementary in Cherry Hill, students observe Patriot Day with an assembly. It's part character education - teaching students good values - and part nod to the day, principal Bob Homer said.

"We ask them to remember the brave patriots who have perished in pursuit of liberty - not just on 9/11, but throughout history," he said.

Last week, Sharp's fourth and fifth graders, whom Homer believes are old enough to learn a bit about the attacks, wrote about what they can do for their country. Some will read their work at the assembly.

"For kindergartners through third graders, it's tough for them to understand," Sharp said. "I will say how we have a great country, and so many people sacrificed their lives for our country, and that's why we say the Pledge of Allegiance every day."

Kean, the former governor, said there were teaching opportunities at every level.

"It's got to be treated as a unique event," he said. "Depending on the students' age, you can get into everything from historical perspective - Osama bin Laden didn't come from nowhere - to some of the problems with American government."

According to a study of how texts and curriculums treat 9/11, just four of nine textbooks mentioned the number of people killed in the attacks or say who was responsible.

"9/11 and Terrorism: 'The Ultimate Teachable Moment' in Textbooks and Supplemental Curricula," published last year in a social-studies education journal, found that none of the materials asked students to think critically about the attacks.

The materials "didn't necessarily do a great job of putting it into context of other terroristic attacks," said a coauthor of the article, Jeremy Stoddard, associate education professor at the College of William and Mary.

Michael Cohen, a psychologist who advised Rudy Guiliani on how to speak to New Yorkers about the Sept. 11 attacks, said schools - and parents - should tackle the subject.

"What an extraordinary moment for schools to pull together the piece of contemporary life and make it history," he said.

Even students who view it as a historical event are touched in some personal way, Cohen said. Most know someone in the military, or hear parents talking about national security, gas prices, oil dependence.

If younger students ask if people are still trying to hurt America, Cohen said, adults should be honest.

"You say, 'Yes, there are people trying to hurt us, but we do a lot of things to make sure it won't happen again,' " he said.