Stephen Ritz (@greenbxmachine), award-winning educator and founder of Green Bronx Machine, had the 700 attendees of PBL World on their feet and ready to change the world, one project at a time, after his high-energy keynote to kick off day 2.

A three-time veteran of the PBL World podium, Ritz has seen the STEAM project he launched in the Bronx, New York’s poorest Congressional district, grow into a global phenomenon. His students not only grow tons of fresh food to feed their community but also get a taste of entrepreneurship by designing and installing green roofs and green walls for paying clients. “We’re growing citizens,” he says, and rekindling hope.

Calling himself “the world’s biggest PBL fan,” Ritz recounted the dramatic improvements in student achievement and engagement that have unfolded since he first turned his classroom into an urban farm. For teachers who think “we can’t do it here,” for lack of resources, Ritz pointed out that he’s managed to achieve these impressive results in an aging building that has no windows.

Ritz has nicknamed himself the CEO—“Chief Eternal Optimist”—and doesn’t let lack of opportunities get in way of his students’ success. In the South Bronx, he and his students are reclaiming abandoned buildings and turning broken asphalt into lush urban gardens. His strategy: endless resourcefulness.

Ritz was recently honored as one of 10 finalists of the Global Teacher Prize (@globalteacher), which gave him a chance to share his story on the world stage at a gala event in Dubai. PBL World actually has two finalists of the Global Teacher Prize in attendance. The second is Cameron Paterson (@cpaterso) from Australia.

As @greenbxmachine has captured the world’s imagination, Ritz is finding himself in unexpected situations. He recently met Pope Francis, who shares the Bronx teacher’s passions for environmental sustainability and social justice. Ritz and his students have cooked alongside the White House chef.  His students track the adventures on the Green Bronx Machine Facebook page (like them here).

Disney and other media outlets have shared the Green Bronx Machine story, and another documentary from Upworthy is in the works. Ritz has given two TED talks (here’s the latest), which have gone viral, thanks in no small part to his memorable delivery and catch phrases. (A sampling: “When we teach kids about nature, we teach them to nurture.” “Growing citizens in the best project of all.” “Change what you can’t accept.”)

Such a big success story may be unimaginable for teachers who are just designing their first projects, but Ritz is quick to point out that he started small. His advice for PBL newcomers: Be authentic to students’ interests. Give them ownership. Most of all, he says, “Love them.”

For teachers eager to get off to a fast start with PBL, Ritz recommends the Tower Garden Challenge. It’s free to download from PBLU and addresses all the project design elements of Gold Standard PBL.

PBL World continues through Friday on the campus of Napa New Tech High School. Follow the conversations with the Twitter hashtag #pblworld. Watch for daily blog posts for keynote highlights and interviews, and catch more highlights in the PBL World community on Google+.