"Comrade parents, please stand over there," the woman pleads with us, a warm smile lighting her matronly face.

Before her, dozens of adults and hundreds of children mill about the pleasantly shaded side yard of Moscow's Special School No. 5, greeting each other after the three-month summer vacation. As the teachers, whom one once humorously described as "our Politburo," work through the crowd, order emerges.

Soon, the students-- more than 600 in the school's 10 grades-- are lined up in their uniforms beneath plywood class markers.

It was the first day of the new school year in the Soviet Union. All over the vast country of 262 million, similar scenes were repeated in its grim industrial cities, ancient towns and isolated hamlets as the centrally directed educational establishment swings into action in the 62nd year of Soviet power.

More than 40 million Soviet youngsters took up their pens, texts and notebooks to start the fall semester Sept. 1.

Among them are our three children.

The older two, Cornelia (Nina), 11, and Brennan, 10, are in the fourth form or grade. With the exception of certain fundamental differences to be explored in later installments of this series, their class is the general equivalent of an American fifth grade. Nina and Brennan are now veterans of Special School No. 5 which they entered in the fall of 1977 when our Moscow assignment began. They have become bilingual.

Chandler, 7, entered the first grade today after two years at the Anglo-American school and a year's weekly Russian lessons at home. The three are among a small group of foreigners of all kinds-- from Bulgarians to Indians-- who attend school No. 5 by virtue of the fact that it is just across broad Kutuzovsky Prospekt from the large, fenced compound where hundreds of foreign families live under the watchful eyes of round-the-clock entrance guards.

THE SCHOOLYARD IS AWASH in flowers, each child from cherubic 7 to pimply 17 clutching a bouquet for the teacher, an ancient Russian custom. Whatever our pride at our newly minted first grader, it is as nothing to the shiny emotions of Soviet parents and grandparents clustering around their own beginning shkolniki. Fathers with cameras dart like paparazzi, and babushkas brush tears from their eyes as the little ones line up.

European Russian families seldom have more than one of two children, and each step of the way to maturity is occasion for another pulse of the ineffably Slavic mixture of joy and heartache. The first day of school is one of those steps.

But there is also more here than meets the eye. Among the reasons that this is an important moment is that in the Soviet system, First-grade teachers take the same students through the first three grades. According to Soviet educational officials, this approach has several advantages: ensuring that immature children who may have adjustment problems are not passed from teacher to teacher, and providing a longer time for a caring teacher to fully grasp the potential of all her students at a time when they are most vulnerable.

By keeping teacher and students together for three years, the Soviets foster the concept of a tightly knit collective, run by a single authority figure who hones the sense of mutual responsibility for each individual's actions.

The unstated converse of this is that a perennial laggard may find it difficult to get a fresh start in the crucial formative years of school. As for the impact of collective thinking and will upon an individual, it is an uncommon factor in most American schools.

THE UNIFORMS ADD to the sensation of solidarity, but the scene is still a rich mix of individual tastes. The boys wear handsome navy blue gabardine uniforms and white shirts for opening day. In the fourth grade and above, most add the red neckerchiefs of the Young Pioneers, the Soviet youth group.The boys carry ersatz leather backpacks for their books.

The girls' uniforms are long-sleeved, wool-blend dresses of chocolate brown with removable white lace collar and cuffs and a white apron with frilled shoulder straps. On normal days of the six-day school week, Nina will wear a black apron.

These uniforms cost about $20 apiece and resemble the uniforms worn by public school students in many European countries. The girls' dresses come with extra material at cuffs, waist and hem to be let out as the child grows. Many girls are able with care and some effort to wear the same dress through their entire school career and retire it upon graduation.

While the school sharply discourages the wearing of rings or other jewelry, doting babushkas frequently hand-make the lace collars and cuffs and some girls are wearing heirloom lace that has graced three generations of Soviet students.

No one expects the boys' uniforms to last forever, despite the fact that the only Moscow outlet for them is the Detski Mir (Childrens' World) Department Store in Dzerzhinsky Square in central Moscow, across from secret police headquarters at the Lyubyanka Prison. The lines at Detski Mir in the last week before school are legendary, perhaps rivaled only by the crush at the flower stalls in the farmers' markets around town the night before school opens.

TO AN ADVENTURESOME fanfare from a battered trumpet and the trooping of two red flags of the school's cadre of Young Pioneers, the student body and parents are exhorted by the school's principal that we have special responsibilities in view of the 1980 olympics in Moscow. The school must excel and honor the capital city and the students must themselves excel and honor themselves and the school as well.

For this school and about 100 others like it in the 1,100-school Moscow grade-school system, excellence is not only a matter of pride, but of intense personal interest on the part of the parents. Special School No. 5 specializes in the teaching of English as a foreign language to its students, beginning in the second grade. Mastery of English can mean wide horizons for these children in later life. That is why the elite of Moscow try to send their children there, and why parents monitor their children's performance with a scrutiny that many Americans would find unusual, if not suffocating.