. . . But at the same time, a Rand, McNally & Co. survey of students included in "Who's Who Among American High School Students" found that nationally high schoolers seem to be getting more conservative Only 8 percent of those who responded during the 1978-79 school year admitted smoking marijuana, and the same percentage favored living together before marriage. In 1972, 27 percent said they smoked pot, and in 1971 about 47 percent supported cohabitation. In addition, two-thirds of those in the recent survey favored censorship, while in 1971 a majority opposed it in any form. Seventy-eight percent said they had not had sexual intercouse and 87 percent said they would not have a child without being married. The survey covered 50,000 of the 355,000 students included in the '78-79 "Who's Who." A Rand McNally spokesman says that the survey has shown over the years that teen agers as a whole aren't the activists they have often been made out to be. "What's been overlooked by the chroniclers of youth is a whole group of kids who never succumbed to the trends of the times, the nation's outstanding teens." But his elite group is not immune to the winds of change: Three years ago, 43 percent felt a woman should have both a career and a family to be fulfilled. This year, the figure was 32 percent. Three-fourths of this year's sample said that religion played a significant role in their lives. In 1972, the figure was 63 percent.