The flawless sky set the sunny tone, and the foreign performers lent an exotic flavor, but the children of all sizes romping through Wolf Trap Farm Park were the most memorable sight at the International Children's Festival that began yesterday.

On the last long weekend of summer, children were as interested in rolling down hills and trying out hula hoops as they were in absorbing international culture at the park in Fairfax County.

Five-year-old William Evans, of Springfield, with a frog painted on his face, remembered last year's performance of Chinese acrobats that drew him and his parents back again this year.

"Since last year, he has demanded to come back," said Patti Evans, William's mother. "I didn't think a 5-year-old would remember," added dad Rick.

Over at the popular brass-rubbing table in a workshop tent, Hannah Zytnick, of Potomac, was trying to juggle two wet spin-art paintings, a baby bottle and three children.

"We weren't sure what to expect, but we were happy to find all the performances," said Zytnick, as her husband went to stand in the lei-making line.

Amid the corn-cob printing, sheep shapes and other crafts, there was an attempt at communicating a meaningful message. Children were invited to contribute their vision of how the world should be on a mural to be used in a candlelight vigil preceding a World Summit for Children.

For most of the youngsters, their message was abstract, generally a blur of watercolors swished on with a decided effort to cover as much territory as possible.

In its 20th year, the festival is designed as a cultural exchange where children can learn about customs, dress and arts. Featured this year are a children's choir from Puerto Rico, folk dancers from Bulgaria, a ballet company from Colombia, a youth band from Costa Rica and a folk sport presentation by 11- to 13-year-olds from Taiwan.

Bob McGrath of "Sesame Street" filled the park's Filene Center for a variety show that kicked off the festival, which continues today and Monday from 10 a.m. to 4:30 p.m. Yesterday's crowd was estimated at 8,400 by organizers, who expect a total of 35,000 people to attend during the three days.

Among the American performers were Fairfax County students who did acrobatic routines. Several have been practicing acrobatics for up to five years after taking a circus class.

The young performers from Taiwan are in the middle of a tour that started last week in San Francisco and Chicago and will continue in New York and at Disney World.

After exchanging culture yesterday, however, the group planned a brief return to the familiar. Lunch was planned at a Chinese restaurant in Springfield.