Susanna Sullivan of Reston finished 20th at the 2016 Olympic marathon trials while working full time as an elementary school teacher. (Cheryl Young)

There are no medals, trophies or race photos anywhere in sight in Susanna Sullivan’s fifth-grade classroom at Haycock Elementary. Other than the blue-and-gold Notre Dame pennant that hangs behind her desk, there is no indication of Sullivan’s life outside of school.

Anyone who visits Sullivan during the workday would walk away without knowing that the 27-year-old math and science teacher in Falls Church is also an elite runner who has competed against some of the best in the country.

In the world of elite amateur and even semiprofessional running, there are a handful of competitors who work full time. But few of them finish in the top 10 in prize-money races such as the Cherry Blossom Ten Mile Run or top 20 at the U.S. Olympic marathon trials. Sullivan has done both.

And even fewer do so while working a tiring, round-the-clock job that requires standing on their feet for most of the day.

“It’s not just a 9 to 5,” Sullivan said. “It’s a very emotionally demanding career. You have 29 little people that are going through a lot of stuff. … There are a lot of emotional demands.”

On Sunday morning, Sullivan will be one of more than 15,000 registered runners lining up for the Cherry Blossom Ten Miler in Northwest Washington. She placed eighth in 2014 with a personal best of 54 minutes 31 seconds and 10th last year. It will be Sullivan’s first race since late November, which came a few weeks after her car was rear-ended on the way to work, an accident that led to a series of hip and hamstring injuries that have impacted her training.

Sullivan will be going up against a stacked field that includes defending champion Hiwot Gebrekidan of Ethiopia and Americans Aliphine Tuliamuk and Lindsay Flanagan. Both U.S. runners are full-time sponsored professionals.

Olympic 1,500-meter gold medalist Matthew Centrowitz, who moved back to the Washington area this year, will highlight the men’s field in his debut appearance.

Susanna Sullivan, 27, often wakes up at 5 in the morning to get a workout in before teaching fifth grade at Haycock Elementary in Falls Church. (Kelyn Soong/The Washington Post)

There was a point when Sullivan contemplated solely focusing on running. Sullivan knows she could shave a few seconds off her times if she could nap or go to the gym instead of having to grade papers or hold parent-teacher conferences. But the life she chose gives her balance.

“I think having the perspective that running isn’t everything kind of keeps me grounded when I’m racing against girls who have chosen to make it their full-time jobs,” Sullivan said. “Not having one thing being all-consuming helps me be better at all of [my pursuits].”

Sullivan was always the kid on the soccer team who never seemed to get tired. Her older sister, Sarah, joined the cross-country team in high school, so she followed along.

When the family moved from Memphis to Northern Virginia, the Sullivan sisters brought their talents to George Mason High. In her first race, Sullivan finished as the fastest runner on the team. She was hooked.

“I just really enjoyed that there was always something I could do better,” Sullivan said. “That kept me invested and interested.”

She earned second-team All-Met honors in cross-country her senior year and set region records in the 1,600-, 3,200- and 5,000-meters, establishing herself as one of the best prep runners in Virginia. That eventually led to an athletic scholarship to run at Notre Dame. It was time to jump to the next level, Sullivan told herself.

[‘I like to do stuff that scares me.’ Michael Wardian’s quest to test the body and mind’s limits.]

The high expectations came crashing down because of rampant injuries. She slipped on black ice during a long run her freshman season and fractured her pelvis. Other injuries followed, including a fractured foot her senior year.

After graduating in 2012, Sullivan put her frustrating college career behind her and began teaching. But the desire to run was still there. She researched various competitive running teams in the Washington area and found a fit with George Buckheit and Capital Area Runners, a club for four-hour marathoners to high-level competitors.

In 2014, Sullivan was back to her dominating ways. She ran a nation-leading time of 26:51 at the St. Patrick’s Day 8K in Washington and a week later finished second at Virginia Beach’s Shamrock Half Marathon in 1:14:22, a time that qualified her for the 2016 Olympic Marathon Trials in Los Angeles. In her second marathon ever, Sullivan finished 20th (2:41:18) in oppressively hot conditions.

Sullivan accomplished this while teaching full time and going to graduate school at Marymount University.

“You look at the elite start for Cherry Blossom and I doubt there’s one of them who works a full-time job like she does,” Buckheit said. “It’s a rare thing.”

Susanna Sullivan, No. 30, had two top 10 finishes at the Cherry Blossom Ten Miler, including last year. She regularly competes against full-time runners. (Courtesy of MarathonFoto)

On a chilly spring morning less than a week before the race, Sullivan hopped on the track at Washington-Lee High in Arlington for 800- and 1200-meter repeats.

Buckheit stood on the infield and shouted splits to the several dozen runners who showed up for the predawn session. A former elite runner himself, Buckheit has guided several athletes to the Olympic trials, but he has never met a runner with Sullivan’s dedication.

“Her biggest strength can also be her biggest weakness,” Buckheit said, as Sullivan ran her cool-down lap around the school. “Because she trains her [tail] off all the time. She’s a really hard worker, probably the hardest worker I’ve ever coached.”

Minutes after finishing her morning track session, Sullivan jumped in her car and quickly changed into her work clothes. She needed to be at school an hour early to tutor math, something she does three times a week.

On a typical weekday, Sullivan leaves school around 4:15 in the afternoon and goes on a run before heading to the pool. Because her right hamstring has been giving her issues since January, she does aqua jogging for an hour to add fitness.

“I like to feel productive,” Sullivan said. “I don’t do well with down time. I’m working on that.”

By the time Sullivan returned to her Reston apartment, the sun had set. She wants running to be something she does for the rest of her life and hopes to qualify for at least two more Olympic trials. But on this night, none of that was on her mind as she ate her homemade dinner.

Another workout was less than 12 hours away. And she still needed to get her fifth-grade lesson plan ready.

Read more on running:

Why Olympic medalist Meb Keflezighi loves to race alongside amateurs

Fifty years ago, Kathrine Switzer broke a Boston Marathon barrier. Today, more women run than men.

Even Matthew Centrowitz was shocked he won gold in Rio. Now he craves more.