By Jeffrey Smith, The News On 6

TULSA, OK -- Depending on how old you are, you'll remember where you were when you heard about Pearl Harbor, JFK's assassination or September 11, 2001.

If you're an Oklahoman, you remember the 1995 bombing of the Alfred P. Murrah Federal Building. The attack killed 168 people -- the worst domestic terror attack in American history.

"It all comes rushing back, and I'm sure this one will be just as tough as all the rest of them," said Kyle Genzer, who is a Mannford history teacher.

Genzer lost his mom, Jamie Genzer, in the blast. This anniversary represents a sacred transition to him.

"This year symbolizes the year that I've lived longer without my mom than I did with her. So, because I was 14 when she died, and now it's been 15 years since she's been gone. So it's a big one for me," Genzer said.

Genzer is a middle school history teacher in Mannford. He says if he brings up April 19th in class, he's met by a sea of blank stares.

"For the most part, everyone kinda looks at you just in shock, because they had no idea," he said.

But as of last week, teaching the bombing is state law. There will soon be new learning materials, new textbooks.

Genzer says he's thankful that children for generations will learn about the bombing and the victims.

"That community spirit that Oklahoma showed and everyone coming out to our help and rescue, it just illustrated the compassion here in Oklahoma, and really in the United States and worldwide," Genzer said.

Genzer hopes the ultimate legacy of that day is that good, can overcome the darkness of evil.

Genzer is competing in the Oklahoma City Memorial Marathon next Sunday. It's his first marathon and he's running it in his mom's honor.

Survivors and family members of those who died in the bombing of the Oklahoma City federal building will gather at its former site Monday to commemorate the 15th anniversary.