Queens Students Get Water Lessons by Designing Playground Ozier Muhammad/The New York Times Maddalena Polletta, of the Trust for Public Land, using a model to show students how water effects the city and the environment. The sixth graders at Stephen A. Halsey Junior High School 157 in Queens have a tough assignment before them: design a new playground that will transform a sea of black asphalt at their school into a recreational oasis - and, while they are at it, help clean up New York City's waterways. So, in addition to benches, play equipment, ball courts and drinking fountains, their wish list includes a butterfly garden and a gravel-lined turf field. Those features will capture precipitation and prevent it from overloading the city's sewer system, which, in the case of their Rego Park neighborhood, spews raw sewage into Flushing Bay when it rains. In the process, the children are learning about arcane urban infrastructure and bureaucratese, like "combined storm-sewer runoff." And they are gaining appreciation for the absorbent powers of trees and grass, as well as roof gardens, rain barrels and permeable pavers - bricks that soak up water. "I always thought the rain ended up in the Atlantic Ocean and that it was cleaned first," Aryan Bhatt, 11, said. Theirs is one of five new eco-playgrounds that the Trust for Public Land, a nonprofit group, is shepherding through the design and construction process at schools in Queens and Brooklyn. The schools, with asphalt schoolyards, were chosen, in part, for their proximity to overtaxed wastewater-treatment plants. Sites for five more playgrounds are now being scouted. "Each child has a design notebook, and we encourage them to be landscape architects," said Mary Alice Lee, the trust's director of the city playgrounds program. It's our goal to capture one inch of rainwater. The program has unfolded as the city and state formalized an agreement under which the city would pay for novel techniques to address its biggest water-quality challenge. In March, the city committed $2.4 billion in public and private money over 18 years to environmentally sound solutions. The approach is a departure from more traditional methods to control sewage overflow, like storage tanks and tunnels. To help the students visualize the problem, the Trust for Public Land on Thursday brought its aptly named "Sewer in a Suitcase" to Stephanie Lamere's sixth-grade classroom. Inside the case, which was created by the nonprofit Center for Urban Pedagogy, was a model of a city street, with an apartment building, stores and pipes leading to a river. Maddalena Polletta, who works for the trust, poured copper-colored glitter into the buildings to represent waste water, and sprinkled some on the streets for good measure to take the place of dog feces, litter and oil from cars. She then poured a trickle of water into the building and over the streets, and the students watched as it flowed cleanly through one of two clear-plastic tubes into a mock waterway. But when Ms. Polletta poured a larger amount of water, all the glitter gushed out of the second tube. That tube represented a treatment plant's outfall pipe, which discharges raw sewage along with storm water into rivers when it rains, not just in New York but in many aging cities with combined sewer systems. "Sometimes just a quarter-inch of rain will overflow the system," Ms. Polletta explained. Sewage is released into the bay about 50 times a year. Last year, we had more rain than we've ever had before. Then she placed a green sponge on a roof and poured water over it. She squeezed out the sponge to show all the rain that was captured. She did the same with an ecologically friendly paving stone. The students revisited their playground wish list, highlighting items with green stickers that had the potential to absorb some of the estimated 600,000 gallons of rainwater a year that drains from the current schoolyard. The turf field, meditation garden, vegetable garden and grass suddenly had new meaning. Melissa Potter Ix, a principal of SiteWorks, a landscape architecture firm that is working with the trust, used a mathematical formula to show the children how to maximize the field's absorbency. "If we put one foot of gravel under your turf field," she said, "we can capture one inch of rain." Gravel is just the beginning. In a pilot playground at a school in Brooklyn, the Trust for Public Land put a green roof on the storage shed. It outfitted a gazebo with a rain barrel to collect water for a vegetable garden. It sloped a stretch of asphalt toward a second garden. And it expanded the tree beds. The trust has ample experience with conventional playgrounds. In recent years, it has designed and built 54 playgrounds at schools across the city and designed an additional 123 for schools on behalf of the city's parks department. Those were created as part of a city program to increase access to green space by converting schoolyards into community playgrounds. But the trust's latest initiative has a more ambitious goal, as the city prepares for climate change and the increased rainfall scientists say it will bring. "We all have to be stewards of our natural resources," said Christopher K. Kay, the trust's chief operating officer, referring to the children in Ms. Lamere's class. It's essential that this be communicated in a way that's engaging and creative. When they're excited, they'll remember it.