IN the center of the Brooklyn Children's Museum, a giant labyrinth of molecular-shaped cells stretches toward the ceiling. Children and their parents can climb through the clear plastic structure, which winds its way for 37 feet.
''It's really fun,'' says a pig-tailed girl. ''You could go through it all day.''
The large-scale replica of a cluster of diamond molecules is one of many participatory activities geared for school-age youngsters at the Brooklyn Children's Museum, the oldest children's museum in the United States.
Since the time it was founded in 1899, the museum has gained a reputation for innovation in children's museum programming. Now, after a recent change in leadership, the Brooklyn Children's Museum is about to undergo a period of revitalization to maintain its dynamic image.
''We're at an exciting stage,'' says Mindy Duitz, executive director of the museum.
When the Brooklyn Children's Museum was first established, she explains, it was based on the then-revolutionary concept of using objects from a museum's collection to provide hands-on educational experiences for children.
''Today the philosophy of learning-by-doing is used by all children's museums ,'' says Ms. Duitz. ''The difference is how they do it. That's where the creative work comes in.''
Visitors to the Brooklyn Children's Museum enter through a semicircular tunnel lit with multicolored neon strips. The 10,000-square-foot open-space exhibition area is enclosed in a vast glass and steel structure completed in 1977. (The museum was housed in two mansions on the same site until their demolition in the late '60s.) The new building is loosely divided into sections relating to the four classical elements: air, water, earth, and fire.
The earth area includes the molecular structure, a greenhouse, and a natural history exhibit displaying fossils, butterflies, mollusks, shells, rocks, and minerals.
In the air section children can activate a fan to run a windmill. The fire section features a working steam engine. To learn about streams, children can observe water rushing down a wooden trough through the middle of the entrance tunnel in the water section. They can study the motion of waves by climbing a ladder to move a ripple tank, which casts shadows on the space below.
A series of small exhibits displaying cultural artifacts and natural history specimens from the museum's collection are located throughout the exhibition area. The museum's extensive holdings, which make up one of the three largest children's-museum collections in the country, consist of about 50,000 objects in the areas of cultural history, natural history, and technology.
A gallery toward the front of the museum is devoted to larger exhibits. The current exhibit called ''Dolls: Reflections of Ourselves'' displays a colorful array of dolls from various cultures.
The interior space of the museum is composed of a series of levels connected by ramps. This free-flowing design presents some difficulties in organizing exhibits.
''We want to make the museum a more coherent experience for visitors,'' says Ms. Duitz, who expects to implement changes in the exhibition area by early next year. ''There is the potential for much more exciting exhibitions. The challenge is not to let the drama of the building overwhelm the exhibitions. It's going to require some brilliant design, but there are many brilliant designers in New York.''
Regular school-group tours, which are an important part of the museum's activities, have also come under scrutiny.
''We're trying to get a balance of cultural and scientific programming,'' says Lauren McGuinn, assistant supervisor of education. ''We are rethinking our programs and how we define ourselves as a museum. (In museum work) you constantly have to reevaluate what you are doing and examine whether you are meeting the needs of the local community.''
Outside the regularly scheduled school programs, children ages 6 to 14 have access to a resource library where they can learn more about topics presented in the activity areas of the museum. Visitors are also invited to participate in any of six programs offered each day by museum instructors. These activities may include workshops, films, or performances by dancers, musicians, storytellers, or puppeteers.
''That's what makes the place come alive,'' says Ms. Dietz.
On a recent weekday, a museum volunteer allowed children to touch a boa constrictor wrapped around his shoulders. Neighborhood children who visit the museum regularly can help build a wigwam or a thatched A-frame hut as part of the ''Home-In-Any-Shape'' exhibit.
''We straddle a fine line of meeting the immediate needs of the community and serving a larger audience,'' says Ms. Duitz. ''If the museum is fabulous, it does both.