At a television studio on Connecticut Avenue, four Washington public school teachers put on blind-folds yesterday. As cameras flashed on, they started squeezing and smelling apples and oranges, and tried to explain which fruit was which without looking.

The somewhat strange scene was presided over by Henry H. Walbesser, an education professor at the University of Maryland. It will be shown late this fall on WETA-TV (channel 26) as part of a series of 24 programs, designed to explain to teachers and parents the competency-based curriculum being introduced this year in Washington schools.

Walbesser, a baldish man with a bushy blond beard, has been one of the D.C. school system's main consultants in developing the new curriculum, which spells out in unusual step-by-step detail how major subjects will be taught throughout the city.

"We recognise we're not 'Sesame Street' or 'The Electric Company," Walbesser explained, as technicians fiddled with lights and sound systems. "But we're trying to make this an entertaining as possible. We want to get the message across."

The half-hour programs will start on Nov. 1, and will be broadcast for the following 12 weeks on Tuesdays and Thursdays at 7 a.m. Each show will be repeated the same day at 7 p.m., and each week's installments will be shown again on Saturday mornings.

So far about 1,000 of Washington's 6,800 public school teachers have signed up to attend Saturday classes about the programs, and receive college course credits for them.

In addition, the D.C. Congress of Parent-Teachers Associations is planning workshops throughout the city to give parents a chance to discuss the television shows and the new competency curriculum.

"We're using television," said Associate Supt. James T. Guines, "because we want to get a big message across in a standardized way. We want to standardize the philosophy and techniques of 7,000 (teachers), and we want to give our community of 800,000 people one message about what we are doing."

While the TV shows were being taped at the Van Ness campus of the University of the District of Columbia, about 700 teachers gathered yesterday at Friendship Elementary School in Southeast Washington for orientation meetings about the new curriculum.

The teachers work at 14 of the 28 city schools being used this year to test the curriculum. If it leads to improvements in student performance, Guines said, it will be required as a minimum program in all District schools, probably next fall.

The parts of the curriculum now ready in draft form cover reading, English and mathematics from kindergarten through the high school, and science in elementary and junior high grades. Each subject is broken down into a series of behavorial objectives, numbered from one on up.

The curriculum books contain two ways of teaching each objective and three ways of testing it. Students cannot move on to the next objective in a series until they have mastered the last one.

"There's none of that fancy 'educationese' that the kids will be able to 'understand' this or 'appreciate' that," Walbesser said. "We're interested in particular things that children will be able to do. We want them to exhibit very particular behavior."

For example, one objective for junior high schools English is to "give the mood, character traits, and plot of a literary work with 90 per cent accuracy." To reach that point, students must go through a series of 14 other behavioral objectives, which try to break down this rather complex task into all of its parts.

The television programs for parents and teachers follow the same format. Each one has its own objectives, lessons, and test, arranged in a sequence. Walbesser said the purpose of having the blindfolded teachers try to identify fruit is to show a type of performance - naming things - that children are expected to learn.

School officials said the purpose of the research this year in the 28 pilot schools is to "validate" the new curriculum and see whether it really teaches the things it sets out to cover.