Donna Koczaja juggled five balls at once, balanced a juggling pin on the tip of her nose and kept three balls in the air while tossing one at a time to Andrew Love, who also kept three balls aloft while tossing them back to her.
"We're not juggling," Koczaja said. "We're applying physics."
The movement of the balls, she said, shows periodic motion and conservation of energy.
"As the ball goes up, it slows down until it stops for just a fraction of a second," she said.
Balancing the pin on her nose showcased the concept of the center of gravity.
Koczaja and Love, both engineers at the Johns Hopkins University Applied Physics Laboratory in the Laurel area, were among about 25 scientists, mostly women, sharing their enthusiasm for their careers Sunday at a science technology engineering and math (STEM) expo designed to get middle-school and high-school girls interested in science-based careers.
More than 200 people crowded the Howard Room at the laboratory, looking at photographs of Mercury, hearing about South Pole adventures and experimenting with cryptology and paper airplanes.
Andrea Wozniak, 11, said she was interested in "electronics and robotics," and had come to the expo to get ideas about a possible career in science. The Bonnie Branch Middle School sixth-grader and her mother, Lina, spent several minutes learning from Love how to use a gyroscope as a compass.
"You can demonstrate a lot of science with some pretty simple stuff," Love said.
Angela Maupin, 16, a sophomore at Centennial High School, said she had come to the expo to check out potential science careers because "I have an interest in the environment."
Gerry Konstanzer said he brought his daughter, Heather, a seventh-grader at Lime Kiln Middle School, because "I've got a real love of science and I want to see if she does, too."
Heather, 12, said she's "not sure" whether she wants to pursue a science career, but she described the expo is "pretty cool."
The STEM expo, believed to be the first of its kind in Howard County, was organized by Diana Bailey of the Women's Giving Circle, who is a work-force development coordinator for the State Department of Education.
Bailey, who coordinated the program with Dawn Turney of APL's education and public outreach office, said her goal was to provide hands-on activities that would help girls get excited about science.
The scientists at the expo work for APL, Northrop Grumman, the University of Maryland and more. Most said they signed on because they want to share their passion for science, especially with girls.
"I would have loved to have seen some examples of what women were doing in their careers when I was deciding what I wanted to do," said Christina Hammock, an electrical engineer with the Space Science Instruments Group at APL.
Hammock, who used to work at the South Pole and now designs instruments used on spacecraft conducting planetary probes, said, "I love what I do, and I wanted to share it."
Another enthusiastic scientist was Nancy Chabot, who was standing behind a table covered with starkly beautiful black-and-white photographs of the surface of Mercury.
Chabot, who works for the Messenger project, which took the photographs, said the images, taken in January from the Messenger spacecraft, were the first ever to show that side of Mercury. Messenger is an acronym for Mercury Surface, Space Environment, Geochemistry and Ranging.
"It's a whole half of the planet that's never been imaged," Chabot said.
Sharing her interest in science is important to her, she said.
"I love doing things like this," Chabot said.
"It's really rewarding to see other people get excited about space science. I always liked things like this when I was a kid."
She said about a third of her co-workers in the imaging group are women.
"It's getting better, but there is still a ways to go," she said of women in science.