Students at Riverside School spent months conceiving, designing and building these "nature sculptures." But if everything goes as planned, these pieces will vanish by the end of 2007, broken apart by the wind, snow and rain.

This unique exercise, a Marshall original, was inspired by environmental artists Andy Goldsworthy and Nils-Udo, both of whom use natural materials — whether they be sticks, mud, stones, snow or sand — to create outdoor art.

Marshall thought this would be a perfect project for her students. Not only would it teach them about the different facets of art and aesthetics, but they'd get to fool around with dirt and grime. And, really, Marshall chuckles, what could be better than that?

"I am trying to get them to be dedicated," the art teacher explains. "I want them to be utterly creative, to make them able to talk about things, to broaden their horizons." She also wants the teens in her class to understand that art comes in different shapes and sizes and can change over time when exposed to the elements.

"It was sort of like the industrial revolution. It put a new perspective on things," says Jonny Prudek, one of the young artists sitting in Marshall's class on a recent Monday morning. After a pause, Jonny adds: "I think I prefer art as something on a canvas, not a bunch of rocks."

On the other side of the table, Sebastian Jacques, 14, laughs: "He was there for the free pizza."

Jonny grins but says nothing. His project, a bamboo pole with ivy growing around it, is influenced by Nils-Udo's penchant for using sticks and straw to create outdoor masterpieces.

Julia Lecocq, another 14-year-old Riverside artist, says she is pleased with how her piece, the one with the bird's nest, turned out.

"It looks basic, but it's hard to do," she says.

Students have been photographing the work every four weeks to capture each shape's metamorphosis on film. These pictures, Marshall says, represent the tangible artwork and will be copied and bound in scrapbooks for each student to keep.

"It was fun digging," Jacques says, recalling images from last spring when he and Alessio Bechi, 14, erected their artwork on the lawn in front of the campus.

The whole experience "taught me patience," Jonny says.

Adds Julia: "It's a lot of work, but everyone sees it."

Dana Song, quiet up until now, nods her head. "People say the [projects] are nice."

Perhaps she'd like to do more outdoor nature art? Who knows, someone might one day pay her a lot of money to build one on a front lawn.

The 15-year-old artist shakes her head. "I'd feel guilty becoming a millionaire for this," Song says.

Listening to the discussion around the large table in Riverside's colorful art room, Marshall seems pleased with her students' comments.

"I've got a bunch of really talented kids," she says with a sigh.