For three days this summer, teachers gathered at the Flight 93 National Memorial in remote western Pennsylvania to discuss how to teach the September 11 attacks to a generation with no living memory of the event. The questions included which details were appropriate for young students and what victims’ families want their loved ones remembered for, according to the AP review.

The review found that at least 40 US states expect or suggest that public schools address 9/11 in some way. State provisions vary widely in scope, specificity and framing, the AP reported.

The AP reported that about one-third of Americans were born after the attacks and that the cohort is now in classrooms. Al-Qaida hijackers crashed planes and killed nearly 3,000 people in New York, the Pentagon and rural Shanksville, Pennsylvania.

Felt’s brother, Edward Felt, died on United Airlines Flight 93 on Sept. 11.

Addressing the risk of omission, Felt said, “Even worse than getting started wrong or using inappropriate language is the total omission of telling the story.” He added, “That’s our biggest fear.”

In his remarks, Felt distinguished between getting started wrong or using inappropriate language and omitting the story altogether.

The workshop took place at the memorial in Shanksville, where Flight 93 crashed. Teachers worked through what to include and what to leave out for students born years after the attacks.

Across the states reviewed, expectations and suggestions differed in scope, specificity and framing. Felt’s message to the teachers centered on the prospect that their students might hear no account of the attacks at all.