When the Fairfax County School Baord postponed action on a school sex education survey in March by referring the matter to its instruction committee, some observers accused the board of trying to get rid of a hot social issue.

The instruction committee, however, decided last week to toss that hot potato right back to the board. As now scheduled, that potato will land in the school board's lap at its May 8 meeting.

Committee members, who include six of the 11 school board members, say they will recommend that the full board direct the school administrative staff to design a new sex education course in line with the more open approach that parents, in the school survey, indicated they want for their children.

"What we will present will probably not be an answer, but rather a process for the board to follow when it re-examines the sex education question," said board member Ann Kahn, who chairs the instruction committee.

Kahn said the committee will meet at least one more time before the May meeting to iron out a final recommendation.

The sex education questionnaire, which sparked a renewed interest in the issue, was mailed at random to 2,000 parents last winter. The parents were asked their opinion of the present program and whether they believed topics which are currently considered taboo should be included.

The response rate was 51 percent and showed that 7 out of 10 parents wanted a program that includes a greater variety of topics than currently allowed.

While critics have tried to dispute the validity of the survey, school officials say the poll was designed scientifically and yielded a better response than hoped for.

"Most specialists who use random sampling for such things as testing new products will settle for a 20 percent response rate," said Kahn. "Clearly, the board is called upon to say more than 'oh yes, that's interesting.'"

Fairfax County's sex education program is considered by many observers to be one of the most conservative in the area. The course is made up of four 50-minute classes. Teachers are forbidden to mention birth control, homosexuality, masturbation, rape or incest and students who have questions are not allowed to ask them in class, but must submit them in writing. Teachers answer the questions during class -- provided they do not deal with taboo topics.

Fewer than 2 percent of Fairfax County's high school students are enrolled in the course, and students who have taken the class criticize it for being nothing more than basic anatomy or biology.

Many educators agree with that assessment.

"It's a joke," says one school official. "They touch on more subjects in some of the area's parochial schools."

Several school board members, who are part of the instruction committee, said the committee studied the question carefully before coming to the conclusion that the school board must at least study more liberalized courses. Those board members said the committee spent some time reviewing minutes of past school board meetings to determine if they had any "outstanding promises to the community."

"While we would hold public hearings, I don't think that type of thing would be necessary again," said board member Toni M. Carney, recalling that the board conducted 44 public meetings in 1976, the last time the sex education program was reviewed.

The memory of those emotional meetings was painful enough for some board members to say they hope the sex education issue would be "left alone" this time.

School officials say that when the sex education issue is discussed, a number of vocal citizens, with strong anti-sex education beliefs, come to the forefront to protest. The purpose of the survey, they say, was to determine whether those people were representative of other Fairfax parents or a vocal minority.

"That's frankly one of the reasons the survey was conducted," said Kahn. "To see how the community felt as a whole.

"The response made it clear -- but there is still a need . . . to safeguard the rights of those parents who are deadset against it. I think that is done now by asking for parental permission (to take the sex education course) and I don't think that would be changed in any event."

Most committee members say they do not expect the board to plunge into the sex education issue when the pressing matters of budgets and school closings are imminent.

Additionally, members of the committee agree that the process they will outline will be a lengthy one. They say it will "be pressing it" to see any changes in the 1981-1982 school year.