“Most people buy shoes in one color, then they get bored of it,” says Soni. “But what if you could have new shoes every time you wore them?”

Soni spent a week using JavaScript and programming language Scratch to hash out the concept. At week’s end, she pitched a VC, who suggested she create a prototype.

But unlike most budding entrepreneurs, Soni’s end goal was gaining new skills and experience—not a pile of VC cash. That’s the idea behind Alexa Café, the weeklong summer camp where Soni developed her light-up shoe project. At Alexa Café, girls learn to create mobile apps, design video games, produce movies and code with C++.

Alexa Café is an outgrowth of id Tech Camp, a Silicon Valley-based organization started by Alexa Ingram-Cauchi and her mother Kathryn Ingram. Back in 1999, the year it launched, iD Tech Camp drew 250 campers at four locations throughout greater San Francisco. This summer, more than 40,000 boys and girls from ages 6 to 18 will participate at an iD Tech camp in one of 30 states. Programs are held at some of the most prestigious universities in the country, including Harvard, Yale and Princeton.

Girls participate in iD Tech Camp, but make up only about 15% of campers. At the urging of Facebook COO Sheryl Sandberg and YouTube CEO Susan Wojcicki—who’ve both sent their children to iD Tech Camp—Ingram-Cauchi decided to launch a spin-off that focuses on girls ages 10 to 15. After a successful test run in the Bay Area last summer, Alexa Café, which costs $949 per week, has launched in nine locations in eight states, including New York, Illinois and Washington. The number of campers has jumped from 160 in 2014 to 1,400 this summer.

The program revolves around the principles of Sandberg’s book Lean In. “Our research showed that, if these girls were going to go on to STEM areas, this is the age we need to lean them in,” says Ingram-Cauchi.

The Alexa Café curriculum is similar to iD Tech camp, but the setting is different. Images of women and girls are more prevalent in training guides and the room colors are softer. The instructors are all female, ridding the environment of some of the usual teenage anxiety. “It goes back to the stereotypes where both the boys and girls might know the answer, but the boy will raise his hand and the girl will wait to hear if her answer is correct,” says Ingram-Cauchi.

Last summer, Pixar’s director of photography Danielle Feinberg was a guest speaker at Alexa Café. She discussed how she brought her creative spirit to the tech world and has used it to produce animated films. The presentation helped break down the hardcore concepts of engineering and programing into more approachable, visual-driven ways to code.

Zoe Concepcion, 15, is attending Alexa Café for the second time this summer. “I find it easier to work with other girls,” she says. “When I went to a co-ed class, I felt intimated and got flustered and confused. I wasn’t able to work up to my ability.”

Campers are creating wearable electronics this summer, and Concepcion already has her idea. “I want to create an app that makes it fun to remember when to take your medicine,” she says. And in the coming years, she’s thinking about entering the medical technology sector and tackling challenges like finding better ways to take X-rays and improving the accuracy of brain injury scans.

“Coding has helped me think about the world differently,” says Concepcion. “It shows how much detail, time and work is put into everything.”