"Can you say 'Thank you?"' she asks. Her students drool, laugh and squirm, then baby Haley reaches a tiny hand to her mouth and touches it to her outstretched palm, making the proper sign.
Sign language has long been a technique for psychologists working with very young children, but parents over the last decade or so have embraced the practice with special classes, books, DVDs and online programs. Interest is so intense, in fact, that infant and toddler psychologist Rahil D. Briggs wonders whether some parents now see it as a must-do milestone.
"I worry it is being seized upon as panacea in child rearing by marketers wanting to capitalize on very innocent parental desires for their children to do well," said Briggs, from Montefiore Medical Center in the New York City borough of the Bronx.
Parents don't need to spend hundreds of dollars and hours each day on baby sign language, she said. Instead, she suggested starting with a few signs. Patty cake is a sort of sign language, she said.
"When you say 'yeah' and they clap because they are happy, that is a sign," she said.
Briggs and other experts, however, do believe that basic signing reduces frustration for babies and toddlers by helping them express some of their needs and wants before than can say the words.
"It does work," said Mary Benson McMullen, an early childhood education professor at Indiana University with more than 30 years of experience in the field.
Within weeks after they are born, babies begin to understand a bit of what is being said around them, she said. "At 6 months, they are learning more and more words and within a year they are learning hundreds and hundreds of words," McMullen said.
But most children can't speak clearly until around 2. By showing infants the simple signs for words such as hungry, milk and more, most infants will eventually start to use those signs to tell the parents what they need.
"Babies are able to use their hands far sooner than they can verbally address their needs," she said.
McMullen said she was in a preschool classroom recently and watched an 8-month-old boy who become upset when a teacher he liked, named Mona, left the room. The baby used his tiny hands and signed "More Mona hug please."
San Diego mom Monta Z. Briant began studying baby sign language in 2000 when pregnant with her first child. The signing worked so well that Briant began teaching classes to other mothers.
"For the first couple of years I was actually paying to teach the classes. I'd rent the room and only a couple of people would come," she said.
But in 2003, a publisher asked her to write a book about signing for babies. The book has since been translated into six languages. At one point, Target was ordering 700 copies of the book each day, she said. Briant has since created other books and educational materials. Her neighborhood classes are hugely popular. She has up to 70 parents and babies in each of her six-week sessions.
The idea of teaching babies to sign became more popular after the 2004 comedy "Meet the Fockers" in which Robert De Niro played an uptight grandfather determined to make his grandson into a prodigy by teaching him to sign, Briant said.
"It was a movie that everyone saw and it brought it into the mainstream. A lot of people thought it was trick for the baby to do that. Of course, they don't learn with all the drilling and flash cards like they did in the movie," she said.
Indeed, babies don't necessarily learn the American Sign Language way of making every sign.
"It has to be a natural experience between a caregiver and a baby. If a baby starts to do something with their hands and you realize that is the baby's sign for "more," encourage that and recognize that and that is fine between you and your baby," she said.
McMullen said parents and teachers should make learning signs fun and warned parents about the many, many products offering to teach babies to sign. Parents don't need to buy everything and shouldn't feel pressured that their baby has to learn sign language to be on track with other children their age, she said.
The cost of classes varies widely. For example, one San Diego teacher charges $125 for six, 45-minute group lessons, while a Portland, Ore., teacher charges $89 for the same.
Chloey Lisk, 2, began learning to sign at 10 months. She has been communicating with her parents through sign language for more than a year. "From a selfish point of view, it has cut down on my own level of frustration," said her father, Bill Lisk.
When Chloey cries, she often uses sign language to express things like "hurt" or "hungry or "milk."
Bill Lisk jokes that his daughter avoids the signs for "tired" and "sleep" because she doesn't like to take naps. Her parents figured that out through the process of elimination, he said.
Briant recalled that her daughter used sign language at 14 months when she pointed to the leaf on a eucalyptus tree in a park and signed "moon." She thought the leaf looked like the moon.
Around that time, Briant took her daughter to see a friend who was very pregnant and told her that the woman had a baby in her stomach. When the baby came, her daughter made the signs for "bird" and "out."
"We had recently been to the San Diego Zoo and seen hatchlings in the incubator," she said.
In other cases, signing can be vital. One of the babies in Briant's classes spilled scalding coffee on his foot and had to be taken to the hospital. He used sign language while in the back of the ambulance to say that his father was in the car behind the ambulance. He used it again when he pointed to the gauges on the equipment in the emergency room and used the sign for "clocks."
"Sometimes (toddlers) have so much more to say than just their basic needs and sign language can provide nice sharing and bonding experiences for that," Briant said.