There's a lot of things you don't understand when you're only 10 years old. As a fifth grader I didn't yet know how to do long division, I didn't understand matters of the heart, and I never heard the word "terrorism."

I could've went my whole life without learning the latter.

Sept. 11, 2001 is the first day of my life that I remember vividly. I woke up and got ready for school just like any other day. Our morning math class (taught by the school principal) was canceled because unknowingly to us at the time, he was fielding countless frantic phone calls from parents.

To fill the vacant class period, our teacher took us outside to enjoy group reading in the ideal September weather. There wasn't a single cloud in the sky that day, and the air was a crisp fall 70 degrees.

Our class was reading "Indian in the Cupboard" by Lynne Reid Banks. The book, which had also been made into a movie, told the story of Omni and a plastic Indian figure that came to life as Little Bear.

At 10:03 a.m., we heard a loud crash, and the ground beneath our feet and chairs shook. Our principal came outside, whispered to our teacher, and suddenly we were being ushered inside. What we didn't know yet is that a plane had just crashed into an open field near Shanksville, Pennsylvania, only 30 miles away.

A short time later, our teacher informed us of the day's events. We turned on the classroom TV and watched the news as they showed footage from New York, Washington, D.C. and the nearby town of Shanksville.

We cried, not fulling understanding what happened or what any of it meant. A classmate worried for her grandmother who was to be flying across the country that day.

School dismissed early that day, sending us home to hug our families a little tighter and give our parents peace of mind.

But thousands didn't return home that day. Families mourned their loved ones and neighbors who left their home for the last time that day.

The next year, my parents and I drove to Shanksville to visit the site where Flight 93 crashed. It hadn't yet become a National Memorial Site, just simply a fence where visitors left flags, flowers and notes for those who bravely lost their lives that day.

The seven crew members and 33 passengers fought against their hijackers, sacrificing their lives to protect more from suffering the same fate. The flight crashed at 563 miles per hour, only 20 minutes flying time from Washington, D.C. The exact destination for those hijackers will never be known, but those in the White House and Capitol Building that day should give thanks to those 40 heroes.

While at the site that day, I met a young girl about my age whose father was a co-pilot of Flight 93. Speaking with her and her mother that day was heartbreaking. She and I marveled over the motorcycles that came through as part of the first 9/11 ride and posed for a photo seated atop one of them.

About 10 years later, my sister was working for the U.S. Department of Defense, and while visiting her in D.C., my family was able to tour the Pentagon. Of course the historic displays through the hallway were inspiring, but what I remember most was the chapel built where Flight 77 crashed into the building. I remember the light shining through the stained glass windows to honor the 184 people lost their lives, and the listed names of those Pentagon employees and flight passengers.

Sunday I returned to the Flight 93 Memorial as a way to honor those who died 15 years ago. I was surprised to see such a full parking lot and so many gathered to show their respects as well. The open field that once held only a chained-linked fence of cards, flowers and mementos now includes a visitor's center, a memorial plaza and a Wall of Names listing each of the seven crew members and 33 passengers. As inscripted on the observation deck, the site of Flight 93's crash was "A common field one day. A field of honor forever."

I understand the events of 9/11 far better now than I did at the age of 10, but I don't know that I'll ever understand how terrifying it was for those who died that day. I can't imagine the fear in those who stood in the stairways of the World Trade Center and jumped to their death to avoid being burned alive, or going to work at the Pentagon and never returning home. I'd never be able to put myself in the shoes of the passengers and pilots of Flight 93, who, knowing they would die, overtook their plane to save others, or of the families who were left to grieve.

I have lived a majority of my life post-9/11, and it'd be impossible to say that day hasn't affected me. Sept. 11 showed us that tomorrow is never guaranteed and that tragedy affects anyone.

After 15 years, I hope that we continue to honor and remember those who lost their lives on 9/11 because they have truly left a mark on this country and our lives.