It may have been recreational science, but as far as 8-year-old Cindi Hoover was concerned, the cheese experiment was an esthetic failure.

"I wouldn't eat this for a hundred dollars," she announced to a group of classmates as she poked at the milk-colored substance with her tiny fingers. "It's yucky."

Suzanne Chin, 7, patted her piece of "cheese" as if it were pizza dough. "This is sickening," she said breathlessly, her head bent over the curdy substance.

Hoover and Chin had created the cheese from powdered milk, hot water and a dash of rennin, an enzyme. It was one of the experiments students at Flower Valley Elementary School in Rockville have conducted in recent months in an after-school science program called "Hands-on-Science."

Similar experiments are conducted weekly at 66 elementary schools across Montgomery County in a private, nonprofit program described by its acting director, Janet Frekko, as "recreational science, pure and simple."

Classes are taught by teachers and nonprofessionals, many of them parents with science training. Their salaries are covered by fees children pay to attend the program.

Started six years ago by Phyllis Katz of Silver Spring, a former high school English teacher who returned to college to study science, the program is run by the Montgomery County Council of PTAs.

Katz said she wanted to help teach children the scientific principles behind much of what they do every day.

Once a week after school, students meet to make soap bars or rock gardens, experiment with biodots -- a type of temperature sensor -- or watch balloons explode after filling them with baking soda and vinegar.

The sessions are open to students from preschool through sixth grade and cost $25 a quarter. This winter, the students learned about the physical properties of acids and bases. In the spring, in a session on weather, they will make psychrometers, which measure humidity, and barometers.

Charles La Rue, coordinator of elementary science for the Montgomery County school system, said the program "gives students an outlet they might not otherwise have" because of the quantity of experiments.

A summer "Hands-on-Science" session on the body and the environment is planned for 4- to 6-year-olds. By the end of the school year, about 5,000 Montgomery County elementary school students will have participated in the program, Frekko said.

There are also "Hands-on-Science" classes at some private county schools, at 12 public schools in the District and at 47 in Boston.

With a $200,000 grant from the National Science Foundation, the program is to be expanded in coming years to schools in North Carolina, Chicago, Minneapolis, Houston, Portland, Ore., San Diego and Albuquerque.

"I would like to see it as common around the country as scouting troops," said Katz, who has devised a number of the experiments -- and who tried them first with her children, ages 8, 11 and 15, who attend Montgomery County schools.

Katz said the idea for the after-school program came to her after a visit to the Ontario Science Center, a museum where visitors are encouraged to touch the exhibits.

At first, she said, she hoped to begin a similar museum in one of the schools that had been closed by the Montgomery County School Board. As an experiment, she started two after-school classes at the now-closed Lee Community School, one on simple machines and the other in plant identification.

Although the science museum never materialized, there are now 200 "Hands-on-Science" classes being conducted weekly in space being rented from the school system.

Brandy Farrell, a county resident who studied nursing, teaches 10 of the classes at four schools. It is education in a low-pressure atmosphere, she said.

Children "work at their own pace, and they love it because they want to do it and no one made them," she said.

In previous weeks, her class at Flower Valley has made lemon creme rinse, learned to develop light-sensitive paper and created a crystal garden by combining charcoal, laundry bluing, ammonia and salt. Last week was the cheese.

"Now, no one can eat this because it's not completely sterile," she informed her students, "but you can make it again at home."

"What is casein?" she asked the students.

"Casein is a protein. It makes the milk white," said Stacy Powers, 8.

The class has also made spaghetti "dance" by placing the pasta on a bed of baking soda and vinegar to create carbon dioxide. "It goes all over the place," Farrell said.

Chin said her favorite experiment was a soapy one, when the class "mixed detergent and concentrated lemon stuff and food color."

Adam Willianowsky, 8, said he liked the exploding balloon test.

"If you do it right, and no air gets out, it will burst," he said. "It usually gets everyone wet."

As he left the class that afternoon, the last one of the quarter, he asked Farrell for all of the session's "recipes."

"That way you can do them over and over again and you don't have to take the class again," he confided to a visitor.