In a classroom bright with wall decorations, a line of raggedly cut paper pandas stretched overhead, Liana Szeto sat cross-legged on the floor and explained the morning game to the children around her. She would start with five plastic cubes and a milk carton with the top cut off, and they were to close their eyes while she hid some of the cubes under the milk carton. Then they could count the remaining cubes and figure out how many she had hidden.

Perhaps Sparky, Szeto suggested, might make the next guess.

Jesse (Sparky) Manger, a small blond boy in standard-issue kindergarten blue jeans and sneakers, squeezed his eyes shut and covered them with his hands. "Sparky," Szeto said. "Gu yahp bihn yauh gei do go?"

Just as she had all morning -- just as she does for every full school day in a classroom that includes white children, black children, Chinese-American children and a Chinese-Hispanic child -- Szeto was speaking straight Cantonese.

Sparky, whisking his hands away and gazing at the single cube left atop the milk carton, contemplated her question: yes, he could guess how many she had left inside. "Sei," he said. Szeto lifted the carton and clapped her hands in approval. Four, of course, was right.

Liana Szeto, a 27-year-old Hong Kong immigrant who coaxes and performs her way through each day with a vigor that is almost exhausting to watch, speaks excellent English; she learned it both in her Hong Kong schools and in the junior high schools she attended when her family first arrived in San Francisco. But many of her students don't realize she speaks any English at all. From the first day of school last September, confronted with 24 kindergarten children who by and large spoke not a word of Cantonese, Szeto has never used English in her classroom. She uses posters, gestures, games, songs, repetition, theatrics, picture books, field trips and anything else she imagines might help her teach, but whenever she speaks -- from "Please take out your pencils" to "Let's tell the story of the five foolish fishermen!" -- she speaks in Cantonese.

And Sparky Manger's mother Judy, an American Airlines ticket agent who has cringed at most Americans' inability to manage other languages, is delighted. "With China becoming a world power, in his lifetime, it's really going to be beneficial for him to learn Chinese," she said. "I thought he was going to come home and say, 'Mom, what have you done to me?' And he's never once said anything to me about that. He loves it . . . Now he tells me his name is Jesse Wong sometimes."

There is a label in educationalese for the work Szeto is doing with these children, all of whom were sent to West Portal School because their parents wanted to experiment with a teaching method now being tried in at least 18 public school districts around the country. It is called language immersion, and although the teaching varies from school to school, the principle is the same: English-speaking children, principally from homes where nothing but English is spoken, spend either part or all of their days in classes conducted entirely in another language.

In Baton Rouge, La., fourth-grade children last month were discussing the tax system, studying the Louisiana state government and answering written test questions about layers of the atmosphere -- all in French. In Culver City, Calif., fifth-graders were working long-division problems and reading aloud stories about construction workers and shy cats -- all in Spanish.

There is Spanish immersion in Tulsa, French immersion in Montgomery County, German immersion in Milwaukee and Cincinnati. San Francisco school officials, already immersing students into Spanish and Cantonese, are thinking of adding Mandarin. And although some of the programs, like San Francisco's, are too new for any serious evaluation, many administrators have reported results comparable to those out of Canada, where for 20 years public schools have been offering French immersion that University of Southern California linguistics professor Stephen D. Krashen has written "may be the most successful program ever recorded in the professional language-teaching literature."

In the vast new array of efforts at teaching in two languages, no approach has been so carefully monitored, so widely praised for its effectiveness -- and, in one of the more complicated ironies of this whole controversial field, so disturbing to advocates of the more familiar theories of bilingual education, which insist that a child should learn to read and think first in his native language. The vision of these immersion classes, of American-born children learning math and reading from teachers who never address them in English, has prompted opponents of public bilingual education to ask the obvious question: If you can drop an English-speaking child into a special all-Spanish classroom and get him working and thinking in Spanish with no damage to his psyche or test scores, why can't you do the same thing in reverse?

Isn't this a natural way to accustom Spanish speakers to English without having to teach them reading and basic skills in Spanish?

School districts in several states are already trying special all-English programs for Spanish-speakers, and the federal government, both in U.S. Department of Education reports and in increased availability of special funds, has troubled bilingual-education advocates by showing considerable interest in the idea. And the heat this argument has generated -- some teachers and language experts use words like "a crock" and "a crime" to describe the practice of immersing Spanish-speakers into special all-English classes -- is part of a quiet but spirited national debate about America's attitude toward non-English languages, about the role of language in an immigrant society, about the ties between language and the human spirit. 'Cheryl Es Primera'

Show and tell, afternoon kindergarten and first-grade class, Culver City's El Rincon School, just outside Los Angeles. Irma Wright, her black hair curled and a carnation pinned to her lapel, summoned around her a noisy collection of children and announced who would begin.

"Tu no eres primera," she admonished a small blond girl who had clamored to be first. "Cheryl es primera."

The child nodded, resigned to the primacy of Cheryl, and said in English, "Can I be second?"

Thus it went, the children -- nearly every one of them from an English-speaking home -- looking entirely unconcerned that their teacher spoke to them only in rapid, native Spanish. Cheryl showed off a stuffed gray bear that she said belonged to her mother, and Wright asked, "Quien le dio eso a tu madre?" Nobody had given it to her mother, Cheryl answered. "She saw it and she got it in a store."

"Que tiene este oso en la nariz?" Wright asked, wondering what was appliqued on the end of the bear's nose. The children knew a heart when they saw one: "Un corazon!" they cried.

Irma Wright, a Hispanic woman who grew up in El Paso, has been teaching the kindergarten immersion class since 1971, when the Culver City schools opened the first U.S. version of the program that was generating so much interest in Canada. A school outside Montreal, now in its 20th year, had set off the whole experiment when a group of English-speaking parents asked for a dramatic and effective way to teach their children French; by last year, according to an article in the Canadian magazine Language and Society, 115,000 Canadian children were studying in one of the French immersion programs now offered in every province.

Culver City administrators, under the supervision of linguists at the University of California at Los Angeles, followed almost precisely the original Quebec model: no English at all for the first two years (although the children are free to speak English, and the teacher must be bilingual so that she or he can understand and answer); an hour a day of English reading and language arts in second and third grades; and then a steady increase of English teaching time, until by the fifth grade students are doing more than a third of their classwork in English. "When they leave the elementary school, they are functionally bilingual," said Eugene Ziff, the principal at El Rincon. "They can understand, read, write and speak Spanish in a functional manner, and they have done this without losing any of their basic skills in English."

As he has done for dozens of uncertain parents, Ziff pulled out the mimeographed sheet listing El Rincon's most recent scores on the California Test of Basic Skills, which is administered in both English and Spanish to students in the immersion classes. In 1983 the sixth-grade students were testing out at eighth-grade level on English vocabulary and comprehension. Language mechanics and expression, math concepts and computation -- all showed above average scores, and in the case of language expression, far above average. Only English spelling fell slightly short.

As for their Spanish skills, the Spanish reading test scores are not quite up to the averages for native language speakers, but a recent visit to Mary Nabours' fourth- and fifth-grade classroom, for example, was startling: children with names like Jennifer Feingold and Pentti Monkkonen read easily from their Spanish texts, or talked in Spanish about characters in the story they had just finished, or worked in longhand on their definitions.

"Catarata -- cascada." Waterfall. "Caldo -- liquido que se calienta." Broth -- liquid that is heated. Their chatter with each other was in English, but at the small horseshoe table where Nabours worked with one reading group at a time, only Spanish was allowed. Their accents ranged from good to nearly native; Nabours, who is American but lived in Mexico while studying Spanish, speaks with almost no trace of American accent. They discussed words like supongo, suppose, and interes, as in bank interest, and if their grammar was often not quite right, they plowed cheerfully through what they were trying to say. A lively red-haired girl, asked to escort the visitor down to the kindergarten, was asked in Spanish whether she found the two languages difficult to manage, and she said in slightly ungrammatical but entirely unselfconscious Spanish, "No, because I'm used to it."

"They don't have any trouble getting across what they want to say," Nabours said between bites of a sandwich in the faculty lunchroom. "The program encourages creativity in a certain way, but the main thing it encourages -- this is my opinion; I can't prove it, but I feel it in every cell in my body -- is this feeling of, 'I can' . . . 'If I can speak Spanish, I can do anything. I can do math. I can do science. I can do anything.' "

So why shouldn't it work in reverse? Why shouldn't Spanish speakers learn English the same way?

To answer that, teachers like Nabours believe, you must think about English and Spanish and the social roles they play here. The linguists who designed immersion programs like Culver City's have insisted the programs be used only for children who speak English, children who will go straight into an English middle school, children whose families have sought out the second language and who will never, as long as they live in North America, risk losing the language they grew up with. Catering to Ethnic Groups?

One six-school program in San Diego is using the Culver City model on both English and Spanish speakers, immersing them all into Spanish and then gradually working English into half the school day, but its goal is the same as Culver City's -- to encourage bilingualism, and to celebrate the learning and reading of two languages rather than one.

That very notion, the idea that schools should promote bilingualism and should hold advanced classes in both languages, has been thoroughly attacked during public debates over dual-language education for Hispanics. There is still a strong feeling among many teachers and parents' groups that American schools ought to be teaching in English, that offering special classes for bilingual children amounts to catering to certain ethnic groups. Indeed, the word "maintenance," commonly used to describe classes in Spanish for fully bilingual students who want to sharpen their Spanish fluency, has developed so dangerous a resonance now that most teachers and administrators hasten in interviews either to distance themselves from it ("We don't believe in maintenance here") or to confide that they personally believe in it but that the district wishes only to have students move rapidly into full-time English.

So when Spanish speakers are immersed into English, as several Texas school districts are now doing in a state-sponsored pilot program, no one imagines that they will gradually have Spanish worked back in to take over half their school day. The point is simply to teach them English, using techniques that have worked for Anglophones in places like Culver City: Speak nothing but English to the children, but let them use Spanish when they wish; use vocabulary and phrasing aimed at children just learning the language; fill the gaps with posters and pantomime and things the children can touch.

This is what it looked like on a recent morning in Houston: A plump, smiling teacher named Rachel Echavarry, traversing the rows of quiet children, held up small picture cards and waited for each response.

"Jesus, what's this?"

"It's a cat."

"What's this?"

"It's a cow."

"Where is the cow?"

Hesitation. Then, tentatively: "The cow -- is in -- the barn."

There is nothing unique about a class like this; it is standard English as a Second Language (ESL) teaching, offered as part of many public schools' bilingual programs. The difference, at Gregory-Lincoln Education Center and the other Texas schools trying similar approaches, is that Jesus and his classmates are immersed in English all day long -- they are never supposed to hear Spanish from their teachers. Indeed, many of the teachers at Gregory Lincoln do not know how to speak Spanish or any of the Indochinese languages nearly a quarter of the students arrive with; instead, in Saturday workshops and in-class training, they have studied ESL teaching techniques.

How well it works -- whether these Texas children are having an easier time learning English while keeping up in their other classes -- is still in some dispute.

"Thank God for the English immersion," said Linda Hunter, a fourth-grade teacher now at her 10th year at Gregory Lincoln, which used to offer an hour a day of Spanish-language instruction. Her colleague Sherilyn Kozodoy, a third-grade teacher whose class includes two Spanish-speaking children, agreed. "I had students in my former school who had been going to the bilingual classes for three or four years and still had difficulty with the English language," Kozody said. "They learn it much more slowly."

Some teachers are similarly enthusiastic in Texas cities like McAllen, which has attracted national attention for its English immersion pilot; and in Virginia's Fairfax County, which for seven years has insisted on intensive English instead of dual-language instruction. But preliminary Texas data indicates so far that the immersion classes there, experimentally begun four years ago in cities that also offered bilingual programs, are producing English test scores no higher than those from the bilingual classes -- and there are misgivings about the experiment even among some of the administrators in charge of it.

"I had had one teacher start crying and saying, 'Look, I can't do this, it's not fair to the kids,' " said Delia Pompa, Houston's bilingual education administrator. "There were others, to be perfectly fair, who thought it was a good option . . . I'll be honest. I would prefer a dual language program, because I don't know what kind of cognitive deficits the immersion children are going to have four or five years later. And I think there are going to be some."

Wallace Lambert, the social psychologist and language expert who developed the first French immersion programs in Quebec, has argued for more than a decade that to use these techniques on language-minority children is, as he wrote in a 1984 California Department of Education volume, "not only wrong but dangerous." The danger, he argues, lies in what he calls "subtractive bilingualism" -- the elimination in school of the language the child first used to think, to conceive ideas and accept who he is.

"We are not removing their language from school," countered Sally Clyburn, acting instructional supervisor for the Houston schools. "We are removing the language from instruction . . . the students are using their native language. They can be seen walking to the school cafeteria, to and from the playground, using their native language."

"The child is basically being told, 'Your language is not worth anything,' " said William Prather, who teaches in Spanish to English speakers at Rock Creek Elementary School's Spanish immersion program in Chevy Chase and who thinks the approach is entirely wrong for non-English speakers. Teachers like Prather and Mary Nabours believe a child whose language is kept out of the classroom will probably lose much of it, if his is not the language of society at large, and that public schools do children a great disservice that way.

"It's like taking a great gift and throwing it away -- and some of us fight so hard to try and learn a new language," Nabours said. "I understand it's hard to get bilingual teachers. But I also believe America has a real problem in its understanding of the importance of language . . . I don't consider a person educated unless he speaks another language. If you have a child who speaks Spanish, and you don't use that to teach him to read and write in that language, you're stealing from him. And you're stealing from society, because we need people who can speak those languages. "The Value of Native Language

The argument over language immersion is not really about the merits of the few programs now trying in some formal and monitored way to place non-English speaking children in special all-English classes. There are not very many of those programs -- most are either small experiments or are aimed at children like the Indochinese, who often have no bilingual teachers available -- and it is highly unlikely that in the near future they could replace bilingual classes. Federal funds that can be used for special English immersion programs are limited to less than 10 percent of the $139 million budgeted for bilingual education this year.

The battle over that funding was fierce, though, with bilingual education critics wanting much more of the budgeted money to be available to English immersion-type experiments. Bilingual education advocates fought back, some of them declaring that these special immersion classes were simply a convoluted path back to the days when schools openly sent Spanish and Chinese-speaking children to fend for themselves in standard all-English classes -- the kind of approach the Supreme Court prohibited 11 years ago.

So the argument is really about the value and meaning of native language in a child's schooling, and that makes it much bigger and more complicated than the proceedings inside a few public school classrooms. "I think the issue becomes an emotional issue, and people stop looking at what kids need, and what works for kids," said Houston's Delia Pompa. "It becomes in some ways a threat, and sometimes 'I-made-it-why-can't-they,' and sometimes people bring political baggage and emotional baggage to it. I think sometimes people miss the point."