For many Vietnamese immigrants, the memory of April 30 — the day Saigon fell to the Communist north — has been passed on only through photos, stories or video clips. Or it's been buried under silence.

One girl gasps as the grainy black-and-white footage rolls: Women are screaming, thrusting their babies at soldiers boarding a helicopter.

In the next scene, hundreds of refugees packed in the belly of a rickety boat rock in the ocean, desperately trying to flee their homeland after the fall of Saigon.

Gathered in a Garden Grove office, young adults who grew up in the shadow of war watch the images, only tasting the horrors their parents and relatives endured when South Vietnam fell to Communist forces 38 years ago.

For many in immigrant communities like Orange County's Little Saigon, the memory of April 30 — "Black April" to those who lived through it — has been passed on only through photographs, stories or rough video clips. Or it's been buried under silence.

"I was only 10 months when I arrived in the United States," said Giao Tran, 20, a student at Golden West College in Huntington Beach. "I must figure out what led us here. When I ask my dad about his escape, he says, 'That's in the past. We don't talk about it anymore.'"

Now Tran is part of the new immigrant generation trying to keep the lessons of Black April alive.

This past weekend, as their elders donned military dress, convening at the Vietnam War Memorial and the Vietnamese Boat People Monument in Westminster, the young adults gathered to take history lessons from the Union of Vietnamese Student Assns. of Southern California.

"If you think of a history of another country in the world, probably there's nowhere like where we came from," said Phong Ly, 30, who led the discussion.

Ly, an aide to U.S. Rep. Alan Lowenthal (D-Long Beach), retraced the unraveling of Vietnam and its people after 1975, hitting on land reform, mass executions, re-education camps, hunger and isolation.

"When I share stories of Black April and what happened after with my younger siblings, they're like, 'Are you kidding me? I don't believe it.' We who grew up here get everything we need," said Dianna Nguyen, 22, who's majoring in Asian American studies at Cal State Fullerton.

"What we also need," she added, "is to have compassion for the suffering we never saw."

For some, the lessons raise basic questions.

"So — who are the people who stayed back?" Tran asked. "How did someone decide if they were on this side, or the other side?

Billy Le and Nina Tran, among the nonprofit's current leaders, stressed to the group how their fellow Vietnamese live in a nation without open access to the Internet, without fundamental human rights.

"Instead of listening to what the Communist government says, you should look at what they do," Le, 26, urged. "We're youths, we live with Facebook — why do they block Facebook?"

"It's a society based on brainwashing," said Nina Tran, 25, a student at Orange Coast College in Costa Mesa.

By comparison, Vietnamese Americans "can dig really deep into what went on — no one can force us to accept face value," Nina Tran said, adding that it's important for them to lobby Congress on International Human Rights Day and to learn about the people, places and issues linked to their ancestral homeland — including actress Jane Fonda, who opposed the United States' involvement in the Vietnam War.

Nina Tran then takes the youths outside, assigning them to "write down what you consider the five most important things in your life."

The choices are youthfully typical. Money. Education. Career. Social mobility. Technology.

"Give up one of these things," Tran instructs them. "Then another. And another."

Finally, each is left holding one strip of paper. Most bear one word: "Family."

"You gotta give that up too," she orders. "Now you know what your parents went through — Black April and beyond. That's what they were left with: nothing."