At Benning Elementary School in Northeast Washington, where reading and mathematics test scores consistently rank above the national average, three third-graders are being promoted directly to the seventh grade in the fall.

For fourth-grade pupils also are being jumped straight into junior high school.

These great leaps forward, however, are not occurring because the students are doing exceptionally good academic work. Their work, in fact, has lagged far behind.

The seven are skipping ahead in the fall because of their age. Under an old D.C. school system policy still applied at Benning and many other schools, youngsters above the age of 13 1/2 must be promoted to junior high school.

And the way Benning promotes its students also makes its high test scores misleading. Only students who can work at a specified grade-level actually take the standardized tests.

In other D.C. schools, like most around the country, students usually are promoted from grade to grade along with others the same age regardless of achievement. But at Benning - except for the 13-year-olds - there are none of these "social promotions." Students move ahead, Principal Alice Rhodes said, only when they have mastered the work for their grade level.

Thus, many Benning students are considerably older than normal for the grade to which they are assigned.

The sixth grade, because it is "skipped" by so many low-achievers. is much smaller than the first five grades. Many low-achieving students leave Benning without ever taking the sixth grade tests.

According to test reports issued by the D.C. school system, average reading and math achievement at Benning is above national norms. Indeed, for the past two years Benning has been the only D.C. elementary school with a large enrollment from low-income families whose children have consistently scored so high.

But Benning's way of promoting and testing its students in different grades is so different from any other school in the city that test experts say it is treacherous to compare its results with other D.C. schools or with school around the country.

At most schools, about the same number of students take the standardized tests for sixth grade as are promoted to seventh grade. At Benning, however, 26 students took the sixth grade test in May 1978. A month later, these 26 students and 14 others were promoted from Benning to become seventh graders in junior high school. The 14 were students who were jumped from lower grades and not tested as sixth graders.

"It doesn't make sense to put children in a grade and give them a test when they don't have skills to do the work," said Rhodes, who has been principal at Benning since 1959. "We move children along according to the work they can do. But there comes an age when they get so big they have to go to junior high school; they can't profit by staying on here."

Yet, the norms for national tests are based on the grades actually attended by throughout the country. They reflect the widespread policy of social promotion.

"Our norms are appropriate for the normal age distribution of children in different grades," said John Stuart, an offical of the California Test Bureau, which publishes the standardized tests used in Washington.

"They would not be very appropriate if you only allow children to take the test who have given evidence of being able to do grade-level work. That would be a self-fulfilling prophecy because the lower end of the group isn't there."

Stuart added: "If your promotion policies are a lot different than usual, you're really straining the test data to make comparisons with other schools."

Comparisons that show Benning in a favorable light have been made since the mid-1960s, even though several central office administrators said they were not aware of how the school promoted and tested its students.

"We have no central records of what different schools are doing," said Associate Superintendent James T. Guines.

Even if Benning's test data is not comparable to that of other schools, Guines said he still felt Benning is doing a good job.

"In a lot of schools, even though the students are called sixth-graders, they're only doing work at the third-grade level," Guines said. "At Benning, when they're listed as fourth-graders, they really are doing fourth-grade work."

Guines said Benning has been carrying out for many years some of the main themes of the school system's new competency-based curriculum.

"They're giving children work at their own level," Guines said, "and moving them ahead only when they've mastered the material. That's what we want to do throughout the school system."

As part of the curriculum, Guines said, the D.C. school system plans to develop uniform tests that children throughout the city will have to pass at the end of grades 3, 6, and 9 before they can be promoted.

"That will put an end to all the pressure that a school has to promote a child to junior high school when he turns 13.7 years old," Guines said. "If a child does not come up to some specified test standard, then you would hold him back and work with him until he does."

Guines said his staff was developing the New Standards, but he said he did not know when they would be enforced.

Rhodes, the principal, said she agrees with Guines' ideas. But she said her own notions on how to run the school come from experiences several decades ago-she won't say precisely how many years-when she taught in a one-room school with 60 students and seven grade levels in Carroll County, Maryland.

"The only way you could handle that," she said, "was to teach each child at the level where he was and move him along as fast as you could. Now we call it 'continuous progress,' but it's the same idea."

Benning, at 41st and East Capitol streets NE, has 378 students-about 40 percent of them poor enough to qualify for free school lunches.

The students are divided among three large rooms called learning centers. Two of the rooms are as big as medium-sized supermarkets, and six teachers are spread around each, occupying defined areas where they teach specific classes most of the day.

In one room there are about 150 first and second-graders who range in age from 6 to 9. The second large room has about 170 children aged 8 to 13 in grades 2 to 6. Kindergarten and pre-kindergarten children aged 4 to 6 occupy a smaller room with three teachers.

Even though each child is assigned to a grade in official school records, their report cards give their status only be levels, ranging from A to U.

During an academic year, a child making good progress would move up through several levels, Rhodes said. Each level, she said, corresponds to the particular book a child is reading in a standard series of graded readers.

But a child can't move on to a more difficult book, she said, unless he shows on a test that he has mastered the skills taught in the one just befor it.

"It was kind of hard for me to tune into that" said Phyllis Clarke, a teacher assigned to Benning since 1957. "Then I came to understand that what matters is the level where children can do the work, not their ages."

As a result of the system, each teacher's class at Benning contains children with a wide range of sizes and ages-in a few cases as much as four years-but their levels of achievement are about the same.

The pattern is opposite that of most D.C. classrooms, Rhodes said, where the age range is narrow and the span of achievement may be three or four grades.

"Common sense tells you its much easier (for the teacher) to manage if the range in achievement isn't terribly wide, Rhodes said. "But we also try to move each child ahead as fast as he can go, and not get him stuck on one track."

Recently, Alice Bowman, who teaches fifth grade, said she had three reading groups, spanning 1 1/2 years of grade-level achievement. At the start of the term, the range was even narrower, she said, but it spread out as children moved ahead at different speeds during the year.

But what happens to children who get stuck in a grade?

Rhodes said sometimes if they have a good rapport with a teacher they stay in the same class for another year. Others are switched to a new teacher but pick up on the same level of work.

For several months this year 11 older children with serious academic problems were assigned to a class with one teacher in a small room.

"We work with them. We work with them. We work with them," Rhodes said. "There's no such thing as children who can't learn if you work with them where they are and teach them each step of the way."

Indeed, according to its test records, almost every child who goes through Benning has been able to reach a fourth-grade level on the national achievement tests. But the record above that is sopttier.

"I think they're still a pretty impressive school even if they don't test too many sixth-graders," said George Weber, former associate director of the Council for Basic Education, who wrote warmly about Benning in an article several years ago.

"It doesn't bother me that many of the students are older than usual," Weber said. "That's a valid way of dealing with the problem. It's too bad all the sixth-graders aren't held to their standards. At least the school is moving in the right direction . . . But it's not simple. In education these things just aren't simple." CAPTION: Picture 1, Alice Rhodes, principal at Benning Elementary School has an inpromptu discussion with second grade students.; Picture 2, Doris Foggie, a first grade teacher at Benning, receives a showing of hands. By Douglas Chevalier - The Washington Post