Faculty members of St. Agnes School in Alexandria and some of their most promising students of the French language currently are hosting 19 teen-agers from Paris.

In August, 15 St. Agnes students will board a plane to Paris for a reciprocal visit.

The exchange is part of a pilot program to encourage young language students to learn about each country's home life, said Rebecca Fox, chairman of St. Agnes' French department. Denise Glandieres von Swearingen, a St. Agnes faculty member, arranged the exchange involving students from L'Institution de l'Assomption in Paris.

"The idea was to have the girls see what the two countries are like," Fox said. "Not just a school experience but for them to live with families and learn about everyday life in this country."

Twelve of the students -- six from the United States and six from France -- gathered Friday with faculty advisers in a lounge at St. Agnes to talk about their experiences.

Among the things about this country that most impressed the French students are the size of the United States and the scale of everything. "The roads and the cars are so big, and each family has a minimum of two (cars), it seems," said Yasmina Skaff, 16, who is staying with Marijke Smith, 15, at the Smith's family's Fairfax County home.

But the French girls agreed that the people they have met have been the best part of their visit.

"The people are very kind and they don't have any complexes," said Skaff.

Cecile de Sesmaisons, 14, said she also liked the people and then added quickly, "Et la p-age . . . the beach."Skaff chimed in, laughing, "And the jellyfish, too."

The girls were taken to Chesapeake Bay to sightsee, Fox said. Other trips have been arranged by the host families.

Wolf Trap Farm Park also was a revelation to those who attended performances there. "I liked it very much," said Cybele Razimouski, 17.

"We have nothing like it in France."

Two of the most irrepressible of the group were Razinouski and her new-found friend, Linda Trossback, 16.

"I think American families move a lot," Razimouski said.

"She helped us move into our new house," Trossback explained.

Groping for words, Razimouski said she also had seen a large house being moved on tractor wheels: "It was quite strange."

The two girls broke into giggles and Trossback added, "We talk all the time and hardly get any sleep."

Kim Hanson, director of development at St. Agnes, said the French exchange students are "supposed to speak only English while they're here. Likewise, our girls are supposed to speak only French when they get to France.

You can hear that that doesn't always work," said Hanson.

As the French teen-agers groped for English words to describe their impressions of the United States, they whispered helpful instructions to each other in French.

Hanson pointed out that the French program at St. Agnes has produced a batch of top scorers on the advanced placement tests of the National College Board.

St. Agnes requires all students from elementary grades one to six to take French, Hanson said. In order to graduate, students must have an additional three years of French at the high school level.

Kay jones, a member of the French department, said that language and literature are not the only goals of the French program. "We want to teach them the culture as well," she said. "That's why we're so delighted with the exchange."

The French visitors, who arrived here July 13, just in time for a July 14 Bastille Day celebration with their host families, will leave for Paris this Sunday.

St. Agnes students will fly to France the following day to visit not only their friends' homes, but traditional French holiday resorts such as Trouville and St. Tropez.

Julie Garrett, 17, who will stay with Blandine Decaure in France, pondered what she wants to do during her trip. "I plan to eat a lot," she said.