The group turned to talk of mothers-in-law and holidays, and, despite not fully grasping the language they were speaking, the women were eager to share.

"Ma belle-mere . . . belle-mere . . . " one began eagerly. She waved her arms in the air, searching for the words. "Elle est . . . "

"Chienne," she tried - the literal French translation of female dog. When her teacher frowned, puzzled, the student provided the English translation.

"Ah!" instructor Patricia Le Foll said. "We don't use that word like that."

She jumped up and began scribbling on the blackboard behind her, providing two possible French alternatives for the popular American insult. Her five intermediate students eagerly took notes, laughing, promising to remember those words for later.

And through conversations about weekend activities, children and spouses, music and restaurants, they continued to learn French.

Tomorrow marks 15 years of Le Foll's teaching her native tongue to thousands of students at A l'Ecole Francaise, a language school tucked into a few small rooms in a Bala Cynwyd office building. The setting is undynamic; Le Foll is anything but.

That this largely one-woman show has been in business so long, and so successfully, is a credit to a vibrant, passionate teacher with a joie de vivre impossible to fake. During her classes, be it beginning French or advanced French literature, Le Foll is animated and intense, her lips naturally turning upward into a smile or frowning in concentration. "Oo la la" is a legitimate and oft-spoken phrase. She puffs her cheeks and blows out air to demonstrate how "Tant pis" is more like "So what?" than "I'm sorry."

"The school is a very special place and Pat's a special person," said Sandra Barenbaum, a Philadelphia lawyer who has taken private lessons from Le Foll for more than 20 years. "She's so enthusiastic and so hard-working, patient, and knowledgeable. She's just really a pleasure."

Le Foll has built an esprit de corps among her students: Once strangers, they now watch French films together, travel to France or French-speaking Montreal, or caravan to Francophile events such as a film festival in Virginia. They also support one another's activities and hobbies outside French class.

"This school has created my family," Le Foll said. "It is my professional and emotional family."

Le Foll was born in Tours, in central France, but also lived in Africa as a child. Like a well-bred Frenchwoman, she refuses to say how old she is, a practice that she apparently taught her older American female students - they, too, declined to divulge their ages when interviewed.

Le Foll slipped, though, when she mentioned that she was just 22 when she began teaching economics in 1982. She came to the United States to study at the University of Pennsylvania in 1987. She met a man, fell in love, and moved here permanently in August 1988 (she now lives in Wynnewood). She loved teaching, but didn't feel comfortable tackling the complexities of economics in English. Instead, she decided to teach French. After all, she'd always loved language, even publishing a book of poetry during her days as an economics professor.

She began working at six local language schools and for the public school system, teaching French to adults and children. When she decided to strike out on her own in 1994, she took 80 of her students with her (some of whom are still with her today), and started with two group classes. The second year, the number of students grew to 145. Now the school has about 10 classes per session, and claims more than 200 students a year.

"I am a language learner myself and I teach from a learner's point of view," said Le Foll, who works seven days a week, 35 hours in the classroom and the rest in planning and administrative tasks.

The recession has been tough on the school, where private lessons are $60 an hour, group instruction $210 for 10 weeks.

"People will stop taking French before they stop taking yoga," Le Foll said. "If they can't travel, why learn another language?"

But she has seen an uptick in enrollment recently. And she still has her cadre of longtime students, including college professors, lawyers, doctors, and a journalist who wanted to better write and report a story that involved filing papers - in French. Her current crop comprises homemakers, musicians, businesspeople, and retirees.

Their reasons for studying the language differ: Some want to travel or conduct work in French. One lawyer wanted to take on French-speaking clients. Still others want a refresher on those high school courses.

"It's a mental exercise for me," said Montserrat Bonetti, a retired Spanish teacher who gave her age as "in her 70s."

"As a former teacher, I can say the one thing you don't want to do is make your students feel stupid. She doesn't make us feel stupid."

Michal Schmidt, a musician and professor at Haverford College, joined one of Le Foll's beginner classes to expand on the French she learned as a student in Israel.

"I love coming to class," Schmidt said. "Even after work, when my head is ready to explode with exhaustion, I don't miss it. I learn a hell of a lot from these easygoing conversations."

Le Foll created her own teaching method, which she calls "bons sens" or "common sense." It is just that, she said, with an emphasis on conversation and practical skills. Students are immersed in the language and very little English is spoken, even at the most beginning levels. While she requires the same memorization and drills as any language course, Le Foll's is more interactive and, she said, natural. There is a focus on conversation about one another's lives, which teaches the group while enabling them to bond. Le Foll starts each class with a clean blackboard and ends with it covered in words and phrases, including idioms that don't appear in many texts.

"It works. I say that because I don't hear complaints," she said. She bristles when discussing some modern language courses that purport to be faster or more effective. Those courses focus mainly on individual words, Le Foll said. "It takes two years to speak a sentence. In a good language school, it's two months."

Ask Le Foll's students to describe her and they say "fun" or "relaxed," and compare her gestures and expressions to those of an actress.

"I feel comfortable. She's very good at keeping it light but teaching, too," said Betsy D'Angelo, of Haverford, an intermediate student. "She corrects us, but in such a fun way."

But Le Foll said she's not playing games.

"A lot of students don't realize I'm serious. They say I'm funny," she said. "But I really know where I want them to go. They don't waste time."

Then, to a student who is flubbing the past tense of "to be," she said, "Oh! You pretend not knowing to help us learn? Merci!"

She jumped out of her chair at the front of the room, picked up her chalk, and began to write the correct tense. "Et voila. . . . "