A major government sponsored research survey of how best to teach reading has concluded that structured methods that emphasize letters and sounds are substantially more effective with low-income children than informal open-classroom techniques that try to teach whole words and meaning.

The difference in favor of the code emphasis or phonics approach is "strikingly clear" in the first three grades of school, said Lauren Resnick, professor of psychology at the University of Pittsburgh, who directed the two-year study for the national Institute of Education.

However, after third grade when standardized reading tests increasingly measure understanding of complex material, children from poor backgrounds generally score low, she said, no matter what method is used to teach them.

On the other hand, children with stronger backgrounds usually read well, she said, regardless of how they are taught.

The survey of reading is based on research reports by more than 40 scholars throughout the country. Resnick presented its findings at the fall meeting of the National Academy of Education, a prestigious group of scholars.

"We really do know enough now to say that direct instruction works to teach the initial levels of reading," Resnick declared. "As a matter of routine practice we must include it in the early grades."

Resnick said the structured methods teach reading as a code with letters of the alphabet representing different sounds that must be combined according to definite rules.

Although the informal reading methods have no set program, she said they generally try to teach reading by starting with a child's own language and experience. Teachers often write out short stories that children themselves dictate or make use of simple basal readers with a vocabulary based on how familiar words are, rather than choosing words that show patterns of different letters and sounds.

In the Washington school system more than 30 methods of teaching reading now are in use, some with little emphasis on phonics. However, the school system is developing a new highly structured curriculum, which use a step-by-step method to teach letters and sounds.

The new curriculum is being tested this year in 28 schools, and D.C. school Supt. Vincent Reed has said that if it works well, it will be used in all schools throughout the city starting next fall.

In an interview recently, Resnick said the structured phonics approach probably works best because of the nature of the English language itself.

"The sounds of the alphabet are systematic." she said. "Some children may induce the rules themselves, but not everybody can do that. They have to be helped. They have to be taught."

In addition, Resnick said, most curriculums for teaching individual sounds and letters are carefully planned out, unlike informal methods that rely heavily on the inventiveness of individual teachers and the diligence of their students. As a result, the structured methods make sure that children actually spend a certain amount of time on reading words while in informal classrooms the children may just be talking.

"The time on task itself may be the crucial thing," Resnick said. "In the structured programs, teachers control the time and tell kids what to do. When things are more loosely organized the kids may not actually spend much time on reading."

In a discussion among researchers at the meeting, Stephen K. Bailey, of Harvard, the new president of the Education Academy, suggested that the scores on reading tests may drop after the third grade because of the difference between word recognition, which phonics methods can teach, and the process of understanding, a written passage, for whcih no reliable teaching method has been developed. "There's not just one process called reading," Bailey remarked.

Resnick agreed but added, "We might as well do what we know how to do, and then get busy on the more complicated job of teaching comprehension."

Children of well-educated parents are likely to pick up reading themselves without systematic instruction. Resnick said, because they usually have many opportunities to read around the house and also because their parents are likely to answer their questions about letters and sounds no matter what is happening in school.

Resnick said the "biggest evidence" on the effectiveness of structured reading methods comes from a nationwide study of Follow Through, a government-sponsored program in elementary schools for low-income children who attended Head Start nurseries. The program provided funds to try out about 15 different classroom programs, each supervised by experts who devised them.

Resnick said the most structured programs show the best reading scores with the highest being achieved by the Distar, developed by researchers at the University of Oregon. Among the Follow Through schools using it is the Nichols Avenue School in the Anacostia section of Washington.

Resnick added, however, that Distar's advantage faded after the third grade.

Another major study favoring direct teaching methods, she said, was a survey of several hundred teachers in California schools, headed by David C. Berliner.

She said many other smaller studies and research analyses included in the survey also confirm the advantage of the structured teaching methods. She said almost everyone of them has been attacked because of shortcomings in research methods, but she said there is a "recurrence pattern" in the results that is persuasive.