Matilda Begody thumped her ruler at the blackboard, gazed down at the children below her, and waited.

"Dzo," they cried.

She nodded, moved the ruler. Softly, their voices rising with the proper inflection, the children sang out the high tone: "Dzoo?"

On the walls, bright posters laid out the numbers from 1 to 10. Taa' -- three silver bracelets. Tsosts'id -- seven arrowheads. One building over, in a noisy third-grade classroom, an intent circle of black-haired children followed along in their workbooks as a girl among them fixed her eyes on the page and read slowly aloud: "Alchi'ni' t'o'o' hadaazhchxago hoogan go'o' alhaa'a na'a'kai."

The children broke into tears and ran home. This is bilingual education in Arizona's Navajo County, where nearly 150 children -- a third of the enrollment at Tuba City Primary School -- spend at least part of their day working through phonetics charts, arithmetic exercises and simply printed readers in the tonal language of the Navaho Indians. With skeptics even among the Indian elders themselves, a growing number of schools both on and off the reservation are further complicating the bilingual-education debate by offering dual-language teaching in languages that until recently no one had ever written down.

There are more than 200 Indian languages now being taught in American public or reservation schools, according to Barney Old Coyote, the Montana-based coordinator of the National Indian Bilingual Center. A few, like Navaho and Crow and the Alaskan native Yupik, are major languages still so widely spoken that some children from those communities speak little or no English when they first enter school.

But scores of other languages, from Gwich'in in Alaska to Seneca in New York, are being taught to Indian children even as the last fluent speakers begin to die off. When Isabel Johnson, the bilingual coordinator for San Juan School District in Northern California, decided three years ago to begin teaching Eastern Pomo children their own language, she found only 10 people, most of them elderly, who spoke the language well enough to teach even the modest after-school classes Johnson had in mind. Even after she persuaded two to come give the classes, Johnson was faced with teaching literacy in a language that had no writing system.

So, like other Indian teachers who have faced the same problem recently, they invented one. A Hunter College linguist flew out from New York, and over several weeks she and the new language teachers pronounced and wrote Eastern Pomo together until they had developed a word list, a curriculum book for future teachers, and a 35-character alphabet to account, for example, for the seven separate Eastern Pomo sounds that all come close to the English t.

Not all these efforts have been uniformly welcomed by the communities they are supposed to be serving. Shirley Haswood, a Navaho who teaches fourth grade in Tuba City, believes Tuba's students need more English than the Navaho teaching time allows them, and that there is something strained about working so hard to read a language that is still largely oral. "It won't be useful for me because there aren't any books," she said.

And some Indian elders have told bilingual proponents that the native language has no place in public school. "They're afraid the white people are going to learn the language and rip off the whole tribe," said Donna McArthur, who works for a southern Idaho reservation school and has had a difficult time convincing Shoshone-Bannock elders that the language ought to be taught in what is still perceived as the non-Indian institution of elementary school.

Why bother anyway, particularly for public school children who cannot speak the language at all? First, Johnson said, helping Indian children learn their grandparents' language might help them understand family-taught language patterns that contribute to problems with their own English.

And if some of these languages are not transcribed now, Johnson said, they will surely disappear. "It's almost like we're on a time clock, because we saw what happened in Pomo," she said. "There were 10 people out there, and now there's five, besides the kids we taught . . . It's just urgent that we get this stuff on tape and get it in writing, so that even if they're not ready now, the stuff's there so later they can understand some of the language."