The second-graders were very quiet.

They put their hands behind their backs and stepped gingerly onto the turtle-shaped steppingstones, past the yarrow, past the lantana flowers, past the cucumbers and beans. The sun hadn't yet peeked into Cora Kelly School's courtyard, and the grass was cool.

"That's Peter Rabbit's garden," whispered their teacher, Anne Richardson. "Quietly look behind the fence."

There sat a fat gray and white rabbit. He sniffed the air and looked unfazed by the 17 children who were crowded around him, careful not to make any sudden moves or sounds.

Learning to relate to rabbits -- and turtles and frogs and plants and soil -- is a big part of the science curriculum at the Cora Kelly School for Math, Science and Technology in Alexandria, which 11 years ago removed the portable trailers from the blacktop courtyard and replaced them with plant boxes, a fish and frog pond, and crab apple, maple and Japanese snowbell trees.

In recent years, an increasing number of schools in the area have begun similar "habitat gardens" on school grounds. These can range from simple vegetable patches, where children can plant tomatoes and oregano to "grow a pizza," to Asian-themed gardens landscaped by parent-designers.

Said Arlington schools' science supervisor, Constance Skelton: "You can be a very environmentally challenged school with a lot of asphalt on it and still make use of nature. Every school has some trees."

Over the summer, basil and baby lettuce sprouted along the Mall when the Smithsonian Folklife Festival featured Berkeley, Calif., chef Alice Waters's Edible Schoolyard program, which incorporates school-based planting, harvesting and cooking into students' lives.

Many schools in Alexandria, the District and Arlington, Fairfax, Loudoun and Montgomery counties have some version of this. Popular themes include "Beatrix Potter" gardens, with the vegetables from Mr. McGregor's garden; butterfly gardens, where children can witness caterpillars' metamorphosis; and pumpkin patches, where they can carve jack-o'-lanterns from the fruits of their labor.

But where garden activities used to be considered slightly looser than most academics, the requirements of the No Child Left Behind Act have prompted teachers to find ways to tie the gardens to Virginia's Standards of Learning exams, said Wendy Sparrow, who oversees Alexandria school gardens.

That way, she said, as schedules get tight and schools emphasize the core curriculum, teachers can still justify taking their students outside and devoting precious time to what can be learned in the garden.

"Everything's SOL-related that we do out there," Sparrow said. Not just science, she said, but also social studies (agricultural traditions in different societies), math (weighing the pumpkins as they grow), economics (supply and demand) and even literature (planting gardens taken from those in books).

The garden at Cora Kelly includes cash crops, such as cotton, peanuts and tobacco. "In years past, we've tied it in with Colonial times," Sparrow said. Third-graders use the garden to find examples of food chains. Fourth-graders use it to learn about traditional medicinal herbs, including rosemary, which early settlers believed was good for memory; thyme, for sore throats; and fennel, to lose weight.

At Arlington's Science Focus Elementary School, fourth-graders learn to identify native Virginia plants and fifth-graders study Thomas Jefferson's farming techniques. The school has a compost bin and a "rain forest victory garden," whose crops are sold to raise money to preserve the earth's rain forests.

At Kingsview Middle School in Germantown, sixth-graders will soon be using a patch of native Maryland plants to learn about stewardship of the Chesapeake Bay. "They're very conscientious about their place in the environment," said Margy Hall, a science teacher there. "They take it home, and they talk with their parents about it."

For many urban children who live in apartments, such programs introduce new ways to relate to nature.

"They see that there is more out there than just four apartment walls, where you walk out, see a bug and just step on it," said Bill Kay, science consultant for Arlington schools.

Richardson said that after her students learn that bees do not exist solely to sting people, they look at them differently. "They're taught to panic," she said, "but after they spend enough time out there, they begin to relax and don't panic any more."

Funding for the gardens -- the ones at Cora Kelly School cost $600 to $700 a year to maintain -- comes from PTAs, garden club donations and, sometimes, from the districts themselves.

Standing by the school's tiny amphitheater last week, behind the bird feeders and the scarecrow, some first-graders crowded around several box turtles, waiting to see if they could find their way to a plate of melons.

"Now, the turtle does not have the sense of sight we have," Richardson said as the animals crawled around near the plate. "They're going to have to smell them."

"I know why they're box turtles," said Tyrese Randall, 6. "Because they move their head like this," jabbing his head forward and back like a boxer.

But second-grader Jeremy Nelson, 7, is a serious student of turtles. His job was to notch a baby turtle's shell for identification. He picked up the palm-size animal and, using a fine file, carefully sawed a small groove in the shell's edge.

"It's always a little easier [with babies] because their shell is softer," he explained, furrowing his brow behind blue-framed glasses. "But if you have an older one, his shell is harder, so you get more sawdust -- I mean, shelldust."

Jeremy, who wants to be a zookeeper someday at the National Zoo, brought his father to visit the school recently. "His dad was so excited," Richardson said. "He said, 'He's not a hands-on child -- he's a book child.' So his dad was ecstatic that he was picking the turtles up and holding them."

At the Cora Kelly School in Alexandria, Tyrese Randall, 6, keeps an eye on the habitat garden, where box turtles were feasting on fruit.Saja Ibrahim, 6, takes a closer look at a miniature pumpkin in the garden, which was created 11 years ago.At the habitat garden at the Cora Kelly School for Math, Science and Technology in Alexandria, students hear about the box turtle's eating habits. A teacher told them that the turtle doesn't have as strong eyesight as humans, so it has to rely on its sense of smell.Morning glories, which attract hummingbirds and butterflies, flourish in the habitat garden, which also includes several colorful birdhouses.