The Howard County Board of Education voted today to expand the family-life and sex education curriculum for grades 5 through 8, despite the objections of the board chairman, who said a middle school text on human sexuality should have received more public scrutiny.

The five-member board voted unanimously after a brief debate to include a new film strip, slides and a pamphlet on human reproduction in its fifth-grade family-life classes. They also voted to include a new 60-page booklet entitled "Family Living and Human Reproduction" in the middle school curriculum.

The vote came after nearly two years of planning by educators and parents, who avoided the rancor that marked similar moves in other Maryland counties.

While praising the work of three advisory panels of parents and educators that worked on the changes, board Chairman John C. Murphy did criticize the review process for the new middle school text, a pamphlet that includes a discussion of abortion and sexual intercourse.

Murphy said the booklet, which he called a reasonably good text, should have been included in the broader textbook review process Howard County adopted in the mid-1970s.

Instead, the advisory committee's review of the book was more limited than that for other textbooks, Murphy said. Those books are made available routinely to all county residents, Murphy said.

Other board members, however, said the advisory committee gave parents ample opportunity to review the middle school booklet.