The Brainstorming Smarties, from left: Katie Martin, 10, Buse Arici, 10, Zella Mantler, 10, Audrey Ferguson, 10, Nora Johnson, 9, Kaitlyn Nowinski,10, and, in front, Maddie Brown, 10. (Lauren Lumpkin/The Washington Post)

Christina Headrick calls the decorating scheme in her home “mad scientist chic.” Among bookshelves and family photos are clumps of Styrofoam, specks of glitter and nearly 300 cardboard toilet paper tubes. On the floor, you can see where someone got paint on their foot.

Headrick and fellow mom Emer Johnson coach the Brainstorming Smarties, an all-girls ­engineering team from Glebe Elementary School in Arlington, Va. The seven-member team of fourth-graders is the first in the school district to make it to the Odyssey of the Mind World ­Finals. Hundreds of teams from 25 countries will converge Wednesday in Ames, Iowa, and go head-to-head in the cerebral contest.

The first time the Brainstorming Smarties competed together was at the Odyssey of the Mind regional tournament. Buse Arici, Nora Johnson, Maddie Brown, Kaitlyn Nowinski, Zella Mantler, Katie Martin and Audrey Ferguson went on to become state champions in April.

Odyssey of the Mind is a ­problem-solving competition in which students, from kindergarten through college, use art and technology to solve problems. The program was introduced at Glebe in 2015.

Participants choose one of six problems for their presentations. The Brainstorming Smarties selected the problem called “Emoji, Speak for Yourself,” in which “three-dimensional emoji will be used to communicate the life story of a once famous, but now forgotten, emoji,” according to the Odyssey of the Mind website.

“Our team chooses the [problem] with engineering in it,” 10-year-old Maddie said. The team calls their presentation “an engineering play,” packed with music, dancing and handmade machines. In Headrick’s garage-turned-workshop, the girls have engineered machines using materials that include cardboard boxes and slabs of wood rescued from the trash.

Wielding power tools and hot glue guns isn’t typical for the average 9- or 10-year-old. The Brainstorming Smarties have done their own metal cutting, drilling and even 3-D printing. Maddie’s uncle taught the girls how to sculpt Styrofoam, so they used the material to create a life-size cellphone for their performance.

While girls in K-12 schools tend to enroll in math and science courses at rates comparable to boys, male students are substantially more likely to take engineering and computer science classes, according to data from the National Science Foundation. These disparities persist in college; women received just 19 percent of engineering degrees in 2015.

“When it comes to girls, I think that Odyssey of the Mind is a program that is especially relevant,” Headrick said. “It’s extremely disturbing that only 18 to 20 percent of engineering students in the U.S. are women.”

There is only one other all-girls team from Virginia that will compete Wednesday in the Odyssey of the Mind World Finals, according to a representative.

Every Odyssey team is allowed a budget of just $145, so the girls had to find creative ways to stretch their money. They’ve learned how to make materials by hand. They’ve had to scavenge through the garbage for useful items.

At one point, the team needed pulleys for one of their machines but, at $5 each, the purchase would have pushed them over budget. “We decided to make our own,” Maddie said.

When it comes to creating, not much is off limits.

“We’ve encouraged them to make smart choices with glitter, though,” Headrick said.

In another room, Nora, 9, uses a hot glue gun to put finishing touches on a glittery mask. “I wanted to use a blowtorch,” Katie, 10, said.

“The coach’s job is basically to keep [the girls] safe and don’t let them burn down your house,” Headrick said.

Zella, 10, and Katie have taken over Headrick’s home office. Headrick said the girls taught themselves how to use Adobe Illustrator software to create graphics for their presentation.

“Graphic design is about half of our presentation,” Zella said.

The girls can’t reveal too much about their presentation, but it involves a narwhal, a cat and lots of emoji. One of their machines, triggered by a weighted lever and a wheel axle, displays a thumbs-up sign when something good happens and a thumbs-down when one of the main characters is fired from her job. Another machine was built to deliver text messages. Each machine is part of the Brainstorming Smarties’ eight-minute performance.

Headrick estimates the girls have spent more than 150 hours preparing for their performance since September. The girls said they used much of that time figuring out the details of their story.

“We have disagreements, but I won’t say we really argue a lot,” Maddie said. “I really liked that we got to write down all of our ideas and then clash them all together like a big soup. Everybody gets a say in what you do and nobody’s ideas are drowned out.”

Headrick and Johnson helped the girls organize their ideas by writing them on Post-it notes and sticking them onto a wall.

“It’s hard for them to organize,” Headrick said. “So what we do is put up all the ideas for the story, and then the kids figure out which ones are the best ideas and that becomes their script.”

Lori West, the gifted-resource teacher at Glebe, practices with the Brainstorming Smarties at school during their lunch time. “I feel like they really know their own strengths and know the strengths of their team,” she said.

The girls need all the practice they can get before the three-day tournament starts Wednesday.

Katie, who says she wants to be an architect, said there are benefits to having an all-girls team.

“We’re lucky to have an all-girls team,” she said. “We have more similar interests.”

“I just like being with my friends and having fun together,” Buse, 10, said.