Washington school officials this fall will begin testing in 26 schools a comprehensive new cirriculum that spells out in unusual step-by-step detail how major subjects will be taught in every school in the city.

The new cirriculum, which includes a required series of tests for all students, turns away decisively from the educational theories and changes that marked the school system's past decade during which average achievement fell to low levels and stayed there.

Superintendent Vincent Reed, who calls the new program a "competency-based curriculum," said it will be tried out this fall and if it leads to improvements in student achievement, it will be required as a minimum program throughout the school system.

"Nobody will be able to close the door and do their own thing any more," said associate Supt. James T. Gunies, who has been in charge of drawing up the new program.

"The materials will be standardized, the lessons will be standardized," Guines said. "We're taking the play out. We're taking the guesswork out. We're putting in a precise predicted treatment that leads to a predicted response."

Guines said the new curriculum is based on the work in behavorial psychology of Harvard University's B. F. Skinner, who developed teaching machines and even trained pigeons during World War II to carry bombs and detonate them.

The basic idea, Guines said, is to break down complicated learning into a sequence of clear simple skills that virtually everyone can master, although at different rates of speed.

"If you can train a pigeon to fly up there and press a button and set off a bomb," Guines remarked, "why can't you teach human beings to behave in an effective and rational way? We know we can modify human behavior. We're not scared of that. This is the biggest thing that's happening in education today."

According to Thomas B. Sticht, associate director for basic skills of the National Institute of Education, similar techniques, called competency education or mastery teaching, are now being used in many parts of the country.

Since 1973, Sticht said, they have been adopted by the Army and Navy for basic training and to teach entry-level job skills. They have been used successfully in college courses, he said, and also to teach mentally retarded children who previously had been classified as "uneducable."

"There has to be a well-defined series of objectives," Sticht said, "and a step-by-step cirriculum that gives some way (through mastery tests) to know you have met the objectives. When this has been done well, it has been very successful."

But the system also has detractors who criticize it as rigid and mechanistic.

"We must be very careful," said Lawrence G. Derthick, a former U.S. Commissioner of Education, "about adopting any mechanical system of producing children like objects. There are so many complicating factors in each child - emotional, psychological, the home background, the sensitivity of teachers . . . There is a danger in trying to turn out children like nuts and bolts or steel pins. Human beings are more complex."

Inside the Washington school system the competency curriculum has drawn virtually no criticism, and it has been warmly supported by the Washington Teachers Union, whose representatives helped draw it up.

"Teachers are looking for help," said Harold Fisher, the union's chief field representative. "Of course, they don't want to be put into a straight jacket, but they're looking for a method that will work. They want assistance. They want standards for students. They just don't want to be left out there alone with no coordination, with no system.

Last year, Guines said, about 30 different reading programs were used in D.C. public schools. Teachers could choose whatever textbook or method they wanted, he said, but there was no evaluation or firm advice about what would work best.

Since 1967 when Carl F. Hansen was forced out as superintendent, the D.C. school system has had no city-wide standards of what should be taught or how to teach it.

Instead, as part of the prevailing wave of educational reform, the system has decentralized its administrative structure, giving much more power to parents and local administrators.

"Now fragmentation is one of our biggest problems," superintendent Reed said. "The algebra being taught in one school seems like Greek in another one. Sure, teachers can add some of their own ideas (to the new competency-based curriculum). They should do that. But we'll be saying they have to use these basic materials. There has to be some consistency across the city."

Although the school structure remains decentralized - with six regional superintendents - Reed has put all curriculum-making authority back under the central office of instruction, headed by Guines, and ordered everyone to follow his directives.

Guines himself sees decentralization as "a structural manipulation that had nothing to do with what happens to kids in the classroom" and therefore had no effect on achievement.

"Now we're dealing directly with how teachers teach and what students learn, and that's what will make a difference," he said.

Also, since the late 1960s, Washington has built about 30 new schools and additions using the open-space plan advocated by school reformers. The new buildings have large carpeted classrooms, often the size of supermarkets, which their planners envisioned as informal arenas, offering students wide flexibility and choice and putting an end to "lock-step curriculums" taught in old "egg-crate" schools.

Guines said the new buildings will be used differently than their planners intended.

"The open classroom is a cop-out," he declared. "All these [reformers] used to say, 'God made this child, and there should be a natural unfolding of his capabilities.' That's a bunch of crap. God may have made children, but without the help of people they will never develop. Society is demanding that our students be a certain way."

Under the competency-based curriculum, Guines said the open space schools will not be setting for informal unstructured programs, but for "very formal, very structured, sequential activities."

"The space has nothing to do with this program," he said, "It can be done in an open-space classroom or a traditional one."

Each subject, he explained, is being broken down into a series of behavorial objective numbered from one on up.

"For each lesson there will be a clear, stated objective," Guines said, "at least two different ways of teaching each skill and three (test) items so students can demonstrate they've mastered it."

For example, in reading the new curriculum sets out the order in which different letters and sounds should be taught, and gives exercises to make sure that students learn one before moving on to the text.

This summer the first curriculum books - in reading, mathematics, and elementary and junior high science - are being written by about 100 teachers and supervisors.

Over the next year, Guines said curriculum books in a similar format will be prepared for most other subjects, including biology, American history, and foreign languages. When they are ready, he said, teachers of the same subject all over the city will be required to cover the same material.

Joan Brown, the coordinator of the curriculum planning group under Guines, said that although all students will be required to learn the same sequence of material, the program will allow for differences because students will move up the "ladders" in different subjects at different rates. The brightest ones, she said, will not be confined to work at their own grade-levels but can move ahead as quickly as they can handle the work.

Teachers should add "enrichment" material for bright students, Mrs. Brown said, but she acknowledged that keeping them interested and pushing them ahead to their fullest may be a problem. Teaching top students, she said, is not the D.C. school system's main priority now.

"What's needed is to take care of the broad base of skills first," she said, "because that's what many of our students aren't getting now."

Besides preparing the step-by-step curriculums, Mrs. Brown's planning group is writing lists of skills that students will be expected to have before they graduate from high school.

The D.C. school board voted last month to require minimum achievement standards for high school graduation, which would have to be shown on an "exit exam," instead of allowing students to graduate on the basis of their grades and course work alone.

Mrs. Brown said the standards would be ready in several months, but she said they probably will not be enforced for several years because it would be unfair to expect current high school students to meet them.

"We can't just have goals by themselves," she said. "We have to have a system for teaching them."

In 1970 the school board adopted a reading mobilization plan prepared by psychologist Kenneth B. Clark, which also called for setting clear achievement goals. Instead of recommending a particular curriculum, the Clark plan suggested that different schools and teachers use whatever methods they thought best. It proposed that those whose students made the greatest achievement gains be paid more.

The plan drew sharp opposition from the teachers' union and was never carried out.

Reed, who became superintendent in late 1975, has deliberately left any changes in teacher incentives and pay out of his curriculum plan. He also has deliberately involved the teachers' union in all the planning, and has used consultants sparingly to avoid the charge that the plan is being imposed from outside.

He also has left unsettled the difficult question of what standards of achievement should be expected of students at different grade levels even though the school board has asked that standards be set for promotion to every grade.

Should the standards be the same as national norms, which only about 20 per cent of D.C. students reach now? If they are lower, how much lower should they be?

If they are too low, they are meaningless, school officials say; but if they are too high, and nearly all students fail then it would be almost impossible to enforce them. Besides, Mrs. Brown said, the step-by-step curriculum is based on the theory that students thrive on a series of small successes and too many high barriers would be discouraging.

Although the school board has supported Reed, it occasionally has leaned on him to move ahead faster. The superintendent has been cautious.

Last year, he said, was a "year of awareness" about the competency" based curriculum. This summer about 2,000 teachers took week-long courses on how it should operate. Next year it will be tried in 26 schools with an elaborate system of research to measure its effects. Only after it is "validated" this way, Reed said, will it be required in all schools.

"You have to be patient," Reed remarked last week. "The school system didn't get in this mess overnight, and it won't get out of it overnight even though everybody says we have to."