CHARLOTTESVILLE - Flash mobs assemble in public spaces to dance, protest or do battle with lightsabers.

And at the University of Virginia, thanks to Laura Nelson, they gather to learn.

Once or twice a week, students at the state's flagship public university collect in some idle classroom or lounge for a "flash seminar," an ad hoc performance of pedagogy.

The time and place, professor and students are always different. But the goal never varies: "to find learning outside the classroom," said Nelson, 22, a senior from Westwood, Mass., who is majoring in political and social thought. "To find other people who really value being a student."

With flash seminars, Nelson has found a solution to a hot-button issue in higher education: the dwindling time American students spend engaged in actual learning outside class. Research shows a steady decline in weekly study time, from about 25 hours in the early 1960s to 15 hours today. One influential study is provocatively titled "Leisure College, USA."

Nelson's idea - new to higher education, as far as university officials can tell - helped her win one of the nation's 32 Rhodes Scholarships last year.

"What I love about it is, it's purely for the love of learning," said Teresa Sullivan, university president.

Nelson turned down Yale to come to Charlottesville as an Echols scholar, part of an honors program that freed her to study pretty much what she wished. Before long, though, she and some like-minded friends grew frustrated with how little time their classmates spent pursuing the life of the mind when not in the lecture hall.

"I found it difficult to find an intellectual community here," Nelson said.

U-Va. is one of the nation's top public universities, a campus of overbooked overachievers, well-rounded students pulling down good grades even as they juggle busy schedules filled with athletics and nonacademic extracurricular activities. It's a routine of resume-building shaped by the elite high schools that provide many of the university's incoming students each year.

"Participating in extracurriculars is an important part of U-Va., but sometimes it's a distraction," said Lily Bowles, a junior from Northwest Washington who helped Nelson launch the seminars.

Nelson was a product of the same culture. She played varsity field hockey in her first year at U-Va. and took leadership positions in various student organizations. But she came to view those activities as a digression. She quit field hockey because it required too much time and started searching for ways to tap the university's rich intellectual capital.

In fall 2009, she launched a weekly e-mail called Engage UVA. It was a simple list of scholarly events on campus, sent every Monday to a group of about 20 friends. A classmate, senior Anna Duning, built it into a newsletter with a subscriber base of 1,500.

Nelson doesn't take sole credit for the idea of flash seminars, which she says evolved "collectively"out of conversations among friends. She seized on it, though, and mapped it out in a series of online documents last summer: Nelson and her friends would seek out their favorite professors. Faculty would choose topics, assign any readings and set enrollment limits. Students would find teaching space.

She thought about approaching university leaders for approval, but she couldn't think of anything in her plan that required approval.

"It's so simple, and I think that's what caught people off guard at first," she said.

On Sept. 13, U-Va. anthropologist Richard Handler taught the first flash seminar, "Liberal Arts in the Era of Late Capitalism," to an audience of 16 gathered inside Pavilion VI, part of the Academical Village designed by Thomas Jefferson. To populate the seminar with students, Nelson simply placed the event in the weekly e-mail blast.

Dozens of seminars have followed, typically with a few days' notice. They always fill up and often have a sizable waiting list, creating the sort of buzz that might affix to a trendy new restaurant.

Participants say the freewheeling format has spawned some inspired topics, from "Is Google Making Us Stupid?" to "The Death Penalty and Victor Hugo" and "To Be Modern and Completely Dependent on Money."

Seminars have touched on matters as sensitive as the homicide last year of U-Va. senior Yeardley Love and the school's involvement in slavery during the 1800s. Sullivan, a sociologist, will lead a seminar this spring on "Living the Good Life."

Historian William Hitchcock led a Veterans Day seminar called "Soldiers and the American Imagination" and found it "one of the highlights of my fall semester." Students, drawn not by a quest for credits or grades but from pure curiosity, arrived with "a sort of open mind and an enthusiasm that teachers just love," he said.

One evening last week, students gathered for a seminar, "How Do Americans Understand the Civil War," led by historian Gary Gallagher. The setting was casual - a circle of couches and easy chairs in a lounge on the ground floor of an academic building, with 15 students and two plates of cookies.

Nelson started the session by asking students to tell "what caught your eye about the seminar." One student said she liked "to get my liberal arts in when I can." Another said her adviser had cited Gallagher as "a must-hear lecture." A third remarked, enigmatically, "It's personal in my family."

Gallagher held the group in thrall with a primer on common misperceptions about the war, such as the notion that Southerners and Northerners held dramatically different views on racial matters.

"By our standards, all Americans were racists in the middle of the 19th century," he said. "It's an American problem, not a Southern problem."

He implored students to seek out the memoirs of Ulysses Grant and the major speeches of Abraham Lincoln. "And if you can read all of that and still not be interested in the Civil War, then you should move to New Zealand."