Dunn Loring Elementary School is the picture of the traditional schoolhouse: red brick, white painted door and trim and only 180 pupils inside.

Terraset Elementary School in Reston is a harbinger of the future: buried underground and topped with a space age configuration of metal webbing that captures the sun's rays for heating. The school has about 1,100 pupils.

Dunn Loring is the smallest and one of the oldest schools in Fairfax County; Terraset is one of the largest and newest. The two schools illustrate the extremes in public school facilities in the country.

By the size and appearance of [WORD ILLEGIBLE] have little to do with the kind of elementary education Fairfax County youngsters receive, school officials say. However, they find it difficult to convince parents who support either kind of school that both, up to a point, offer equal educations. Complications arise when a school grows too small like Dunn Loring, or too large, like Terraset.

Dunn Loring, built as a WPA project in 1939, will close next year because of its declining enrollment, which is expected to dip to 154 by September. Approximately 300 students at Terraset are being organized into another elementary school and will leave the school in September.

"For each parent, it is how 'my child' is doing that counts," said Nathaniel J. Orleans, planning director for Fairfax Schools. "There's no clear split down the middle among Fairfax parents as far as a preference for larger or smaller schools.Much depends on what kinds of schools a parent is already familiar with."

There are distinct physical differences between a school such as Terraset - with its four open bay areas containing "classrooms" divided by portable screens - and aschool such as Dunn Loring - built, along the traditional "egg crate" design with rectangular classrooms lining both sides of tile corridors. But even with those differences, the similarities are indeed striking.

For instance, at Dunn Loring, as at Terraset, students work clustered in groups, rather than in rows of desks facing a blackboard. At Dunn Loring, as at Terraset, students often are grouped according to their skills and the subjects they are studying. At both schools, groups of children meet for reading or story sessions in their centralized library-media centers.

A detailed "Program of Studies" governing all Fairfax elementary schools outlines for Dunn Loring and Terraset teachers what material must be covered and how much time each day must be given to subjects like language arts (reading, writing, spelling and grammar), mathematics, social studies, science, music, art and physical education. Both schools have programs for advanced and remedial students.

There is a big financial difference, however, in providing the same studies at the two schools: It costs $160 per child to operate Terraset while it costs $489 per child at Dunn Loring, according to one of four special task forces studying student enrollment in difference parts of the county.

"I wouldn't be surprised at that figure," said Dunn Loring Principal Corinne F. Jeffries. "You have to have the principal, librarian, cafeteria staff and custodians no matter how big or small the school."

The size of classes are set by state law, so whether it's Terraset or Dunn Loring, a third grade class, for example, cannot have more than 28 pupils. Because Dunn Loring's population is so low (the school can hold 68 more pupils than it has) when a third grade class exceeds the limit, a new class combining third and fourth graders is formed because there are not enough third graders to make two classes. Most of Dunn Loring's seven teachers have classes combining two grade levels.

Both schools have their supporters and detractors. Kathy Chavez, president of the Dunn Loring PTA who fought hard to keep the school open, says the smallness of the school allows each student individual attention not possible in a big school.

"We have every advantage of a large school and sometime pluses," she said. "In a larger school it's more difficult for a gifted and talented child, for example, to come to the surface. At Dunn Loring, because everybody is so close, it's apparent right away. It's like a small family there really."

On the other hand, Betsy Smith, a Dunn Loring parent and one of 40 parent volunteers who work at the school, said students have more opportunities at a larger school.

"I know of one child personally who had problems with one teacher," she explained. "Everyone thought he would be better off in another class, but there just wasn't another for him to enter."

Terraset parents also view their school differently. Linda Singer, Terraset PTA president, thinks the futuristic school can handle large numbers of students and still give enough individual attention.

"The overcrowding maybe stops us from having the plays and movies and extra things we might have under normal conditions, but it doesn't hurt the the teaching," Singer said. "I have a daughter in third grade who has a class with two teachers for 60 kids. She gets lots of individualized attention from one teacher while the other takes care of the group. These team teaching techniques use the space well so you don't feel lost at all."

But Kathy Linse, another Terraset parent and one of 90 volunteer aides there, believes the school's open structure can distract students from learning.

"An open structure like Terraset is different than an open teaching philosophy, where you can group kids according to their ability even in closed classrooms like Dunn Loring has," Linse said. "The difference is that a room with four walls gives the teacher complete control. She can create quiet just not possible at Terraset."

The debate of big versus small, open versus closed is never ending among both educators and parents. School officials seem to have chosen a middle course to follow in building future schools.

"It depends what you mean when you say 'open' school," Orleans said. "It's clear the community has backed off from wanting the completely open schools popular about 10 years ago, but at the same time, we're not building the standard egg crates. We build schools now that have some of both."

He said most elementary school construction aims to house 660 pupils, although as the state demands smaller classes in the future, fewer pupils will be able to fill those schools. Some larger schools like Terraset also are in the offing, such as a new school for Burke Center, which will be built in 1980 if a proposed $39.7 million school bond issue passes in an April 4 referendum.

Thirteen out of 124 county elementary schools can hold more than 800 pupils and eight of those can hold more than 900. Most county elementary schools can hold more than 800 pupils and eight of those can hold more than 900. Most county elementary schools range in size for 400 to 600 pupils. Orleans said more schools for 990 pupils would be built if growth patterns showed most of the pupils attending those schools could walk to the school.

School officials have not discussed building more smaller schools, although existing ones would not be categorically phased out if they are well attended. The fate of older, smaller schools will become more clear once a countywide task force study of declining enrollment is completed and studied by the School Board.