A dozen children and their parents leaned over a pier jutting out into the Rhode River, a small tributary of the Chesapeake Bay. They launched Popsicle-stick boats to judge water currents. They scooped up water to see what lived in it. They measured wind speed and direction by waving pink strips of paper tied to pencils through the air.

And they beseiged Ann Coren, a freckled woman with a magnifying glass around her neck, with questions.

"Ann," asked Jason, age four."Why are barnacles hard?"

"Ann," asked Billy, also four. "Why does this fish go 'boing'?"

"Excuse me, Ann," said a mother tentatively. "We seem to have lost our experiment overboard."

Coren teaches kids and their parents to explore the ecology of forests and waterways at a part of the Smithsonian far removed from the bustle of the Mall. The Chesapeake Bay Center for Environmental Studies - thousands of acres of forest and fields in Edgewater, Maryland, and a string of islands on the Eastern Shore - has been part of the Institution since 1965.

The center devotes most of its energies to studying the area in and around the Chesapeake, this country's largest estuary, or mixed fresh- and salt-water region.

"Anyone with a boat can see the Smithsonian 'No Trespassing' signs from the river, but not many people know much more about what goes on here," said Sharon Maves, who helps coordinate programs to explain the center's functions to the general public. "In fact, older people remember when the land at the end of Contee's Wharf Road," which leads to the center's cluster of offices and laboratories, "was a big partying place.

"The public thinks of science as asking grandiose questions and getting answers," she continued. "They think of mad scientists in white lab coats forecasting the future."

The center belies that notion: Most of the scientists wear jeans or jogging shorts, and they try to examine specific, limited phenomena of nature. Even then, they often don't succeed in answering the questions they set out to explain.

The center's education department acts as a bridge between the expectations of the public, which wants to hear about sweeping conclusions, and the scientists, who never seem to want to make any. For example, in a woody glade next to Muddy Creek - named for obvious reasons - small flags mark a spot where ants feast on bits of canned tuna.

"There are more than 60 species of ants here and we can't figure out why," said Megan Wood, who runs a film series at the center. "The law of nature usually dictates that there is only one species of animal per habitat."

This ant experiment has lasted for several years, and, at times, the staff has kept a 24-hour vigil to observe how and when the ants search out their food.

"The results of all this will be published in a journal, which will only be read by other scientists directly interested in the field," said Wood ruefully. "We don't end things up a whole lot of fanfare around here."

Nor is there any wish to. Both the Edgewater and Eastern Shore locations are left as much as possible in their natural state, and the staff members have adapted the mood of quiet purposefulness that belongs to the wildlife surrounding them.

Across the bay, Poplar Island once housed a small community, but now only manager Mike Passo and waterfowl and other small animals live there permanently.

Visitors include the scientists engaged in research projects, Smithsonian officials in search of an isolated retreat and, during the summer, anyone interested in participating in the center's organized activities.

"The area is definable," said Maves. "That helps kids understand what goes on, like how the deer population lives in an enclosed space."

Maves also aims the activities at the adults who tag along. "We try to explain things on two levels of sophistication," he added, "although we find that the adults get as much of a kick from the hands-on things as their pre-school kids do." CAPTION: Picture, HANDS-ON LEARNING OUT IN THE WOODS. By Sally Gucinski.