Jason Cawrse shows how new locks on the Panama Canal will work. Inside the model are aluminum-foil boats made by GEMS girls at an engineering event last month at the National Building Museum. (Astrid Riecken/For The Washington Post)

Malavika Nair was in her element. She had shaped one piece of paper to hold 1,500 times its weight. She had dipped her hand into a bucket of water to test water pressure. Now, she was trying out software that lets kids design a virtual bridge.

This wasn’t homework or even an extra-credit assignment. Malavika and dozens of schoolmates from McNair Elementary in Herndon had come to Washington early one Saturday morning for Discover Engineering Family Day.

“This is one of the best field trips I’ve ever been on,” the sixth-grader said.

Girls Excelling in Math and Science (GEMS), the after-school club that brought Malavika to the event at the National Building Museum, was the reason behind her excitement.

“I started liking math and science after I got into GEMS,” said Malavika, who joined last fall.

Dr. Cady Coleman, retired NASA astronaut, speaks to attendees at the Girls in STEM event held last April at the White House (From Elizabeth Vandenburg)

That comment got a smile from club organizer Laura Reasoner Jones, who started GEMS nearly 20 years ago after looking for math and science activities for her own daughter.

“When we started, I had to recruit people,” Jones said. Now, the club holds a lottery because there is space for only 50 fourth- and fifth-graders, and more than 50 sign up. (Jones started a separate group, Junior GEMS, for third- and fourth-graders four years ago.)

Word has also spread beyond McNair. Thirty other Fairfax County elementary and middle schools have clubs. Prince George’s County has a few. So does Atlanta, Georgia.

Jones credits the group’s popularity to the hands-on activities and group projects related to science, technology, engineering and math — STEM, for short.

“We always do things that are not related to science tests or math tests,” said Jones, who is a technology support teacher at McNair. “We always do things that are a little wacko.”

GEMS members are quick to share their favorite club activities: dropping eggs off a ladder in student-designed protective containers and building a tower of pasta that could support a marshmallow.

“We used pipe cleaners to make a cube, and put it in dish soap,” said Isha Kanshal, 11. “It made square bubbles.”

Isha said the girls always form a hypothesis — what they think is going to happen — before they experiment. She said she doesn’t worry if the results are different from the hypothesis.

“Then you learn something,” she said with a shrug.

The atmosphere at weekly club meetings is part of the reason GEMS members are willing to try things that don’t always work, Jones said.

“There’s very little of the pressure of competition,” she said.

Jones said she hopes the interest in GEMS will lead to more young women choosing careers in science, technology, engineering and math. A 2009 survey by the Census Bureau, the government office that counts people and their jobs, found that women made up about half of all working people, but most were not in math and science careers. Women filled only 24 percent of those jobs.

“It has to connect to a career,” Jones said of club activities. “We want them to think, ‘This is fun. I could do this.’ ”

McNair’s GEMS members are already thinking in that direction. In a small group at the Building Museum, there was a future chemist, a future engineer and a girl debating between two careers.

“I want to become a zoologist,” said Shristi Nadkarni, 9, a first-year Junior GEMS member. She paused to consider her options but didn’t stray far from her original plan. “But if not, a biologist.”

READ: More opportunities for girls

Christina Barron