Pulitzer Prize-winning playwright Paula Vogel walked with purpose along South Street on Sunday, more than 40 people in tow. To pedestrians trying to get past them, this must have seemed a tour with no purpose at all.

Occasionally they halted. Then “On to our next stop!” Vogel would signal.

They paused at a mix of places - Harry’s Occult Shop, a Caribbean restaurant, a pizzeria. Isaiah Zagar’s Magic Garden of mosaics, a playground on Lombard, a Starbucks, an alley. Each time, someone would talk to the rest about the place where they stood.

If you’re a theatergoer and could see under their winter bundling, you might have recognized a few of them. One was Quiara Alegría Hudes, the Philadelphia-bred playwright who wrote the book for In the Heights, the hit Broadway musical whose national tour opens Tuesday at the Academy of Music. There were high school members of Philadelphia Young Playwrights, and their mentors from the University of the Arts and elsewhere, and a dozen major artists whose work is regularly visible on professional stages across the region.

This little walk, in fact, had a very clear purpose. The participants had devoted much of the night before to a surprise playwriting assignment; in an hour, these sites would figure in playlets ranging from realistic to freakish, written by members of the group and sight-read by themselves and others.

“The whole aim is to push yourselves,” Vogel had told them earlier, to encourage experiment. “These are exercises. This is all throwaway writing. None of it is for prime time. We’re not writing Long Day’s Journey Into Night.”

Nevertheless, they had taken a long night’s journey writing for Paula Vogel. That meant something.

Vogel’s Playwriting Boot Camp has acquired special status in the theater world as a place where seasoned writers push themselves onto intellectual routes they might not normally travel.

To most theatergoers, Vogel is a playwright whose 1998 How I Learned to Drive won a Pulitzer. But in the theater world itself, she is a powerful and electrifying voice in the classroom for a generation of playwrights trained by her at Brown University or now at Yale, where she heads the playwriting program. One of her Brown students was Hudes, whose In the Heights is here through Sunday; later this spring, Flashpoint Theatre Company will stage her road-trip comedy, 26 Miles.

Vogel has staged her boot camp across the country and outside it - in Brazil, using a translator, and recently in Montreal, where French-language and English-language playwrights faced off over the use of language. Sometimes a camp lasts a week, and participants jump into writing exercises during the day, playwriting each night.

Glen Knapp, who runs Young Philadelphia Playwrights, saw Vogel give a four-hour boot camp at a convention in Denver two years ago, and immediately understood why she was a playwright others look to for inspiration about their art. “There was a stampede for her session,” he says.

At first, Knapp thought he would ask Vogel to do a weekend boot camp for teaching artists involved in Young Playwrights, which mentors 1,700 school-age children in Philadelphia and its Pennsylvania suburbs, some as young as 8.

Then the camp expanded to include some of the organization’s leading high school playwrights, and a larger group of professionals.

Knapp found support from the Pew Trusts-driven Philadelphia Theatre Initiative, which has helped boost the region’s professional theater community into a minor local industry, and from the University of the Arts, where he’s an adjunct faculty member. The camp took over the university’s Arts Bank theater, at Broad and South Streets, last weekend.

On Saturday morning, Vogel moved around and through the circle of participants in constant motion, an animated fireplug of a woman, dressed in black, with a shag of white hair and a clear voice that both invited and commanded attention.

She attributed much of what she said to others - the theater philosopher Bert O. States, her own teachers, playwrights here and abroad. She built on a basic premise - that individual voices can make the everyday seem strange and the unreal real. “I’m going to throw out little things to stretch our muscles,” she said, and then she did, with points that invited comment or provoked thought.

Then came the first exercise: Write a page of a play that would be impossible to stage.

Participants sat on folding chairs or sprawled out in corners, computers and legal pads on their laps. After half an hour they (or, full disclosure, we; I was among them) shared a few of these.

What about depicting total destruction? What about a play that repeats itself endlessly?

The pieces made people think about - and discuss - whether there is anything, in fact, that defies staging.

Working lunch: Write a monologue that conveys many particulars about the person speaking, without their actually being said. The group shared some of these and attempted to describe the characters (body language, dress, age), an exercise that explored not just the writing, but the perceptions people bring to the theater when they watch a play.

The afternoon brought some theater theory beginning with Aristotle, and a discussion of the factor of time in storytelling.

Then - shock: homework!

Use an obituary from a recent Inquirer or a description of a person wanted by the FBI as a springboard for a short play. Choose a fairy tale and tell it as a play. Go to a South Street site (she assigned them), do some basic reporting, and write a five-page play set in the place using three elements you find there.

The room itself seemed to breathe easier when Vogel said the assignments could be combined.

Sunday morning, the South Street tour, which was held so all would know what had inspired the overnight plays, began with some of the notable theater artists among those pointing out the curiosities: playwright Michael Hollinger; choreographer-actress-playwright Karen Getz; director-writer David Bradley; Kathryn Petersen, who writes People’s Light & Theatre’s popular pantos; artistic directors Blanka Zizka (the Wilma Theater) and Jennifer Childs (1812 Productions); actor-playwright James Ijames; and actor-director Pete Pryor.

Then came three hours of the playlets, with everyone assembled on the Arts Bank stage.

The pizzeria at 12th and South became a place for an acrimonious discussion that slowed, then stopped, as a corner trafic light turned yellow, then red. The alley attracted a solicitation, but one only hinted at. The occult shop’s array of objects now included a mysterious woman in a bathtub. At the playground, three mutts wondered at human stupidity. Grandma ran the Caribbean restaurant, and a mysterious man - maybe the Big Bad Wolf - lived upstairs.

Student playwrights called on professional actors to come read - and vice versa. No two plays were alike. The mood in the theater was triumphant. Paula Vogel had trouble saying goodbye.