It takes 5 playgrounds to wear out these preschoolers

There's a happy coincidence of history, natural beauty, and ''the ultimate playground'' at the Country Day School in McLean, Va. Situated in an antebellum farmhouse on five acres of pretty Southern countryside, the school provides charming halls of ivy, ample room to run and play, and a perfect spot for children to begin developing a love of nature.

All this, however, was not quite enough for the director, Dorothy McCormick. With great respect for what nature had already provided, she wanted to create a playground that would not only challenge and delight the children, but would enhance their opportunities to develop perception, motor skills, and overall fitness.

The result of this dream is a 12-station fitness and nature trail that weaves through five separate playgrounds. It includes equipment designed to develop the skills of toddlers and preschoolers, including kindergartners. The 12 pieces of equipment are integrated into a linear trail with brightly numbered signs attached to, or placed beside, each piece of equipment. A trail of markers to guide the children has been placed along the path.

The nature trail runs parallel to the fitness trail. Seventeen species of trees and plants are identified with attractive signs that indicate the name of the tree and the number of meters the child has run. A four-year-old, named Kerstin, got the giggles when her teacher read ''Deciduous Magnolia'' for her. But now Kerstin knows what ''deciduous'' means.

Although the trail runs through all the playgrounds, each is designed to be of maximum benefit to a particular age group. The children identify the playgrounds by names of featured trees.

''Dogwood'' is especially for 18- to 24-month-old toddlers. It includes a slide, stairs, spring platform, balance beam, rocking boat, swings, and sandbox. The striking characteristics of this area are variety of activity and safety of environment.

''Giving Tree'' offers 2- and 3-year-olds advanced stairs, overhead ladder (about four feet high), and stumps for stepping and balance, along with the traditional swings, jungle gym, slide, and sandbox.

''Mulberry'' invites the 3s and 4s climbing parallel bars, Z balance beams, climbing pole, a good old-fashioned tire swing, and slide-playhouse combination. The most charming feature of this playground is an old tractor, hidden in a grove of mulberry trees, for climbing and pretend plowing.

''Walnut'' is well suited for the 4s and 5s, including such traditional equipment as a platform slide, connected truck tires, and tricycles. Popular innovations here are a two-story wooden pavilion with roof (using as its core structure an ordinary jungle gym), chinning bars on three levels, and one ''sit-up'' bar at ground level.

''Maple,'' serving 5s and over, has a jungle gym pavilion sans roof, overhead ladder (about six feet high), log cabin, lots of swings, a rowboat-sandbox, chinning bars, and a dome jungle gym.

In addition to the five planned playgrounds, a complete change of pace is offered in the front yard of the school.

Here about an acre of grassy hillside is enclosed by a split-rail fence and surrounded by giant maples. Not a single piece of play equipment appears. This free area inspires happy/mad running, rolling down hill, swinging from low tree branches, and unlimited imaginative, dramatic play.

If you are exhausted by all this activity, it is refreshing to note that there are picnic tables scattered throughout the playground. Of course they are work tables, too!

As the child advances along the trail, he develops in terms of strength, endurance, and coordination; cognitively, through problem solving and learning what he or she can accomplish physically; socially and emotionally, by sharing, gaining courage, and persevering; and creatively, through experimenting with innovative ways of using the equipment.

Of first importance is the fact that each child understand, when using the trail, that she is competing with herself and not with other children. No one needs to be reminded to have fun.

Of course the trail didn't ''just grow.'' Dedicated parents held a highly successful auction to raise the funds.

Wendy Jones, a Country Day School teacher designed the trail, in consultation with Wayne K. Good, an architect.

Even the construction was accomplished from within. The school bus driver, Jesse Smoot (best friend and best help to everyone at the school), happened to be an expert carpenter. The beautiful trail is a tribute to him.

And the children's reaction to all this? They are just too busy to answer. But if you look closely, you will notice that the kindergarten girls are still chasing the kindergarten boys, just as they probably did in the days of the one-room school.