Although Howard County students tend to do well on nationwide science tests on the average, the quality of science instruction varies widely among county schools because of inadequate funding, crowded classes and a shortage of expert teachers, a committee of county scientists maintains in a new report to the school board.

Acknowledging that the county's science program is relatively good, the committee nonetheless reported that effective teaching is more often the result of "extraordinary efforts" by individual teachers rather than a well-designed and implemented countywide science program.

Robert W. Ridky, a University of Maryland geology professor who headed the scientists' committee, said the evaluation is intended to turn a science program that is already considered good into a model of national excellence.

"From classroom to classroom you don't see a sense of consistency," he said. "We want to make those kind of changes that would put it at the top."

The study, which evaluated science instruction from kindergarten through high school, was undertaken by 54 residents of Howard, some of whom have children attending county schools, said Phyllis Utterback, a specialist in school program evaluation.

School Superintendent Michael Hickey acknowledged the critical nature of the report, but said it contained "no surprises." He said the school system's achievement in science "speaks for itself."

Howard students had the second highest average in the state last year on the math component of Scholastic Aptitude Tests, finishing just behind students in Montgomery County. Howard students who took SAT achievement tests in physics and chemistry scored above the state and national mean, but scored below Montgomery students, a schools spokesman said.

At the same time, Howard has been the only county in the state to send finalists to the prestigious Westinghouse National Science Talent Search Contest for the past two years.

The committee of scientists divided into six subcommittees, and made 300 classroom visits and conducted dozens of interviews to evaluate the science programs. They found that:

* Elementary school science programs were disjointed, texts did not coincide with curriculum and funding for supplies (95 cents per student) was inadequate. More than 90 percent of the teachers said they paid for some supplies themselves.

* Five of 11 middle schools had below-average laboratory facilities, based on a subcommittee evaluation of the accessibility of safety equipment, class sizes, condition of lab equipment and other factors.

* Funding for lab supplies in middle schools ($1.66 per student) was inadequate. A subcommittee recommended spending $4 per student.

* Middle and high school science programs failed to use computers. Although all schools each possess several microcomputers, none was used in conjunction with science programs. Most of the computers, located in the schools' media centers, were idle for most of the day, the report stated.

* Certified science teachers were not evenly distributed among middle schools. For example, two middle schools judged by a subcommittee to have the best science programs had teachers who were each certified in two different science areas. At two schools with the poorest science programs, only two of the six teachers were certified in any area of science, the report stated.

* Twenty-nine percent of the high school biology teachers were not trained to teach biology; physics teachers at five of eight county high schools were not certified by the state in physics and 23 earth sciences classes were taught by teachers who were not certified in earth sciences.

Under state law, teachers with a general science certification may teach chemistry, physics and earth sciences classes even though they have not taken college courses in those subjects. Such teachers are unqualified to teach in those areas, the report stated.

* Many middle and high school science labs were considered unsafe. Some labs did not include eye washing stations and emergency showers while such aids as fire extinguishers were not in strategic locations. Chemicals often were improperly stored, and students often did not wear proper protective clothing during experiments, the report stated.

The committee recommended a series of improvements, including lowering class size from 32 to 25 students; increasing funding for supplies; upgrading the quality of labs and conducting a thorough revision of school curriculum.

The committee also called for a program to upgrade teacher qualifications at all levels and for the hiring of an elementary school science coordinator and a number of lab aides. It also said that three years of science, instead of the current two, should be required for graduation.

Montgomery County, which also has a highly rated science program, is about to conduct a similar evaluation, said John Pancella, a county school science coordinator.