LOWELL, Mass. (AP) _ An experimental preschool here has the same frenetic bustle and noise of any room full of young children, but the shouts and squeals are in three languages.

Five-year-old Brian Scannell counts to 20 in Khmer almost as easily as he does in English. And when Amarilis Sanabria, 5, isn't talking in Spanish and English, the Puerto Rican native delights in teaching her classmates the names of parts of the human body in Khmer.

And when 4-year-old Sok Pheap Tep from Cambodia proudly displays a paper creation to his teacher, he says, in tentative English, ''It's a yellow kite.''

Educators opened the Demonstration School for 40 children last fall with a curriculum taught in their pupils' English, Khmer and Spanish.

They hope to expand to the fourth grade with up to 250 pupils. If the program headquartered at the University of Lowell succeeds, teachers hope it will provide a model for similar programs nationwide.

''We're not denying the realities of children needing to know English,'' said Libby Chiu, the school's director. ''But we're not going to let that reality overwhelm a child's natural capacity to learn more than one language.''

The school was created to fill a void in this old mill city where 25,000 Southeast Asian immigrants, mostly Cambodians, have settled during the past 10 years.

''Lowell was exploding with kids from Southeast Asia,'' Chiu said. ''There was a lack of classroom space and there was a need for early childhood training for teachers here.''

So educators at the university's College of Education worked with the public schools to develop the trilingual program, which was funded by the city, the college and private foundations.

Half the school's 3- to 5-year-old pupils are native English speakers, with the other half divided evenly between Cambodian and Hispanic students. Parents jumped at the chance to enroll their children and there is a waiting list for next year.

The school day begins with a meeting, conducted in a different language each day, with songs, discussions and a kind of cultural show-and-tell. Later the students split into groups where they learn about their native language and culture as well as that of their peers.

Vera Thong Tith, the school's Cambodian teacher, told one group an ancient Cambodian fable about an ant that helps an elephant by biting a marauding hunter.

She sat in the classroom's Khmer cultural corner, where a poster showed a costumed woman performing a traditional Cambodian dance, and a chart bore colorful animal pictures corresponding to Khmer numbers.

Brian counted in Khmer, getting into the teens.

''Dappram, dapprammoy, dapprampi,'' he said, for 15, 16 and 17, before he stopped, and frowned. ''I don't know that one.'' ''Dapprambey,'' Tith said. ''Eighteen.''

In a corner set aside for Spanish, youngsters sang about a white horse called ''Caballito Blanco.''

English teacher Judy Rogers said the program's goal is not to push the students to become fluent in three languages, but to have them learn their own, as well as English.

''We appreciate their native language and make sure they know it,'' Rogers said. ''But they have to learn English. I ask questions and they know they have to answer in English, because I don't speak Khmer. I'm the one in the minority here.''

And the youngsters learn to appreciate other cultures.

Once, two English-speaking children in the class decided to get married. They chose Amarilis as their maid of honor and, asked where they would honeymoon, they replied ''Cambodia, of course,'' Chiu said.

''When kids go to monolingual schools and then get to high school and have to learn a foreign language for the first time, it's so scary,'' Rogers said. ''Think of how these kids will do.''