In bright, treeless heat less than three miles from the Mexican border, a chain-link fence at Nestor Elementary School sports three signs pointing to the same place - ''Tanggapan,'' ''oficina,'' and ''office.''
''Anything to make it easier to communicate with the parents,'' principal Vic Resendez says with a happy shrug. The signs are aimed at parents who speak Filipino, Spanish, and English.
His talk - like that of many bilingual educators - is of children who can feel proud of the language and culture of their homes, and who can succeed in school from the start while easing from Spanish to English over three or four years.
But what about the mainstream of American culture? The classroom has always been the real ethnic melting pot in this country. Is the English language getting short shrift in the bilingual school?
Many think it is, and that it threatens to create separate language groups in the United States. Bilingual educators like Dr. Resendez think this is a regrettable misunderstanding. His dream - shared by other bilingual educators - is of a generation of children growing up fluent in two languages. ''We must become a nation of languages,'' he says, to remain a great nation.
But Resendez - like virtually everyone in bilingual education - is very careful these days to make one thing clear. The purpose of the bilingual program here is to teach children English as efficiently and successfully as possible.
''I think it's a misunderstanding for people to think I'm not here to teach English,'' says Jennifer Schardin, who speaks only Spanish in her first-grade class at Nestor. Her pupils go next door at a certain time each day to a classroom where only English is spoken. ''I'm here to teach English. But in the meantime, I don't let them get behind,'' she says.
The debate over bilingual education is an emotional one with many facets.
There is the education question of what is the best method for making Spanish-speaking youngsters successful in a chiefly English-speaking country. Mexican-American students, many of whom start school in this country with little skill in English. The National Center for Education Statistics reports that the drop-out rate for Mexican-America students is 44 percent nationwide.
Although Congress has sponsored bilingual programs since 1968, whether bilingual education has improved academic performances is still an open question. There have been no conclusive studies.
Then there is the more shadowy question of what is involved in becoming American.
Richard Rodriguez, son of immigrants and author of a 1982 autobiography, ''Hunger of Memory,'' says he believes that bilingual education only forestalls the need for every child from an underclass - as Mexican immigrants usually are - to put away the culture of their parents for the public culture and language of American society.
Many Americans, when talk of bilingual schools comes up, recall grandparents who succeeded by being thrust into English-speaking classrooms to sink or swim. That doesn't make sink-or-swim a good system, Mr. Rodriguez says, ''but behind it is a sense people have that they left something behind to become American.
''I don't feel it is the classroom role to teach children pride in what they were, but to teach them to become something else. . . . Schools should change the child, and make them ready for public society. Sooner or later, a child must make that break with the past and parents' world and join the public world and become an American.''
Many people, especially in the Hispanic community, couldn't disagree more.
Robert Cervantes, a legislative analyst with California's Office for Migrant Education, helped design this state's code for bilingual education. ''All the parents and all the people I have talked to want their children to learn English. That has never been subject to question,'' he maintains. '' . . . But one can become a public person without loss of personal identity and self-worth.''
Teachers in bilingual classrooms are avid about how much better children feel about themselves when they can hear their native tongue in school. ''Look how happy these kids are,'' says Jennifer Schardin, nodding toward her class busily buzzing at math experiments.
Irma Bierman sits in a group of second-graders at 28th Street School in Los Angeles discussing stories they are reading from an English primer. Like many teachers in bilingual programs, Mrs. Bierman is just learning Spanish, and relies heavily on a bilingual aide.
''Sink or swim works,'' she says. ''My grandmother did it. But this way children have a sense of pride in their language and culture.''
The principal here, Robert Tafoya, estimates that 80 to 90 percent of his students are Hispanic and that most of them come to school knowing only Spanish.
The reigning theory in bilingual education is that reading is a transferable skill; once a child learns to read in any language, it is relatively easy for him or her to learn to read a second language. For this reason, bilingual schools attempt to develop basic concepts for children in their best language before switching them into an entirely English program.
Keith Baker, a social science analyst at the US Department of Education, is skeptical of this theory and the studies that support it. He agrees that reading skill is transferable to some degree, but questions whether time spent on Spanish reading is as valuable as spending that time directly on learning to read English.
The one point nearly everyone agrees on, Dr. Baker points out, is that a child should be taught in a language he can understand. But he adds that this is not necessarily the child's mother tongue. It may be most efficient to immerse non-English-speaking children in English, so long as it is geared to their level of comprehension, he suggests.
S. I. Hayakawa, formerly a US senator from California and a semanticist by vocation, is not opposed to bilingual education as a tool in teaching English.
''What is divisive is when bilingual education becomes monolingual education in the immigrant's language,'' he says.
This happens because some teachers, especially those more comfortable in their non-English language, want to perpetuate their jobs, Mr. Hayakawa says.
This happens, but rarely, bilingual educators admit. When it does occur, parents complain and set the tendency straight. Most bilingual teachers in California are non-Hispanic and native English-speakers. So their tendency is to use English more than they think they do.
At Nestor, first-graders may speak 80 to 90 percent Spanish, and more English is added until English dominates in fourth grade. For the children entering school at higher grades without English, the school relies on English-as-a-second-language courses and individual help. This is fairly typical in California.
Roberta Weintraub, a conservative member of the Los Angeles school board, says that students end up staying in bilingual programs much longer than necessary - three or four years - and are simply not learning English. ''I've seen kids graduate from San Fernando High School not knowing English at all.''
Those students are probably recent immigrants, bilingual educators say, and possibly come from poor families, originally from rural areas, that have little literacy or vocabulary depth even in Spanish.
Vic Resendez has national test scores to show his sixth-graders - those he has had from the primary grades - perform well above their grade level on tests given in English.
Tomorrow: tapping Hispanic consumers