About one-third of the nation's elementary and secondary school students - 15 million youngsters - regularly receive instruction by teachers who use television to teach them, a study said yesterday.

The Corporation for Public Broadcasting and the National Center for Education Statistics said their study is their first into television for instruction which is used in more and more classrooms.

CPB Presdent Henry Loomis and NCES Administrator Marie Eldridge said the study comes "when major segments of the American public are expressing concern about the negative effects of television on children."

The $250,000 study, done over two years and finished last spring, reports that 15 million elementary and secondary school students got regular instruction from teachers who used TV as a teaching tool in the 1976-77 school year.

According to the survey, about 50 per cent of the teachers, and instructors "expressed positive attitudes" about TV, while 10 per cent were negative and 40 per cent had no opinion. "That 40 per cent is a crudial target," Loomis said.

Eldridge said it was "interesting, in light of the Zamora case" - Ronnye Zamora, 15, pleaded unsuccessfully that too much television caused him to kill - that 52 per cent of the teachers disagreed with the statement: "Children watch enough television at home: they don't need to watch more in school."

When asked if a re-survey would be made on the question, since Zamora-case publicity became widespread after the study was made, Eldridge said, "That is possible."

Loomis said he would expect not much change, because "public opinion is like a rubber band," and the case would be forgotten. Zamora has been sentenced to a life term for the murder of an elderly woman, and Loomis noted Zamora watched entertainment on commercial TV, not educational TV.