Wanted: Cool start-ups to occupy free "Class A" office space in Center City Philadelphia. Must also be willing to accept free support services and lots of thanks from interns for helping them figure out their lives and get into a good college.

That is the novel concept that Philadelphia's String Theory Schools is heralding this week with the formal unveiling of Particle — a "new type of co-working space" inside the K-to-12th grade charter academy's flagship building at 16th and Vine Streets and a fresh model for education that STS cofounder and chief innovation officer Jason Corosanite sees as a win-win for Philadelphia entrepreneurs and students alike.

Take STS senior Jillian Mayer, for example. When admission officers look at her college application, they will see a student-in-training for the Particle tenant Stimulus that connects funders with community support groups. Someone who has earned real-world job experience writing news releases and posting online articles. And an applicant who has broadened her communications skills collaborating with student-trainee photographers and videographers, graphics designers, computer programmers, and social-media marketers. Plus she's earned incalculable insights from Stimulus CEO Tiffanie Stanard about partnership strategies, networking, and arm twisting. Knowledge "that will help, whatever career path I follow," Mayer said.

Also in residence at STS — offering personal mentoring and classroom visits in exchange for free rent — are the video-game maker PHL Collective (best known as publishers of the game ClusterPuck 99), fashion handbag company MinkeeBlue, and the computer-programming advocates Coded by Kids.

"We just got a grant to start our own [development] shop, focusing on smaller projects that the larger shops aren't interested in," said Coded chief technology officer Michaela Ochnich. "It'll be run by a combination of working tech professionals and our student interns who can get a real-life experience, build out their portfolios, and get paid for it."

In return for their student engagements, these start-ups can use STS resources such as its presentation theater, computer lab, and 3D animation and motion capture studios. This is all paid for, including the $29 million, eight-story, 265,000-square-foot Vine Street building, with a massive (and controversial) $55.5 million bond offering and a little more than $8,000 a year in state funding per student.

Beyond just being interns, there's a DIY start-up mentality brewing internally at STS. Its first-floor, student-run coffee roasting and retail shop, initially underwritten by student-activity fees, is now self-supporting, said Corosanite, and provides the Obura-branded beans featured at three Center City coffee emporiums.

Now the newly finished 5,000-square-foot Particle coworker environs on the eighth floor have added a video-production-friendly test kitchen developed with food and prop stylist-in-residence Lisa Russell. Soon to launch here is a student-run Particle Food YouTube channel — pumping out short recipe videos and product reviews — "that will give Buzzfeed's extremely popular Tasty channel a run for its money," said Corosanite.

Particle's ambitions harken to the pragmatic start-up projects that Penn's Wharton School now encourages from its business students, and to the cycling of classroom study and on-the-job field work long in fashion at Drexel University. The STS strategy also embraces elements of a vocational-technical high school education that traditionally focused on students not attending college.

"Now that's evolved to CTE — careers in technical education — and can be a component of a high-level program for kids who want to be engineers, who want to go into industry," said Corosanite, who holds an educational leadership degree in charter school leadership from Central Michigan University. "It's an experience to give to kids, especially in the 11th and 12th grades, to help them figure out who they are. What's their teamability?

"How well do they manage people, work together? It's part of the String Theory model of intangible elements that aren't really measured in high school. We still appreciate things you can feel and touch, like standardized tests and data. But there are also the intangibles, like innovation, joy, entrepreneurship, creativity. Those are things that might not be measured by tests but may be more of a factor in how successful you're going to be in life."

With nontraditional education advocates swooping in to study and document String Theory's game plan and success — with its "full enrollment" of 3,500 students across two schools and a waiting list of "almost 5,000" — Corosanite aims to take the brand and strategy national.

"We're looking at opening up private schools in other markets — Silicon Valley and Dallas — and to license the school model to other operators," he said. "It is not about providing any additional income to String Theory Schools but rather spreading the model to as many students and locations as possible as we believe it is a fantastic solution to what the future of urban education should look like."