Abstract
Braddock (1974) evaluated adult, expository reading materials for the frequency and placement of topic sentences (main ideas). Results indicated that relatively infrequently were main ideas directly stated in expository prose, and that paragraphs opened with a simple topic sentence only 13% of the time. This study was a modified replication of Braddock's research in which second-, fourth-, sixth-, and eighth-grade social studies textbooks were examined for the presence of explicit and implicit main ideas in paragraphs and short passages. Results were generally consistent with Braddock's findings on topic sentences: only 27% of all short passages that were examined in the social studies textbooks contained explicit passage main ideas; only 44% of all paragraphs contained explicit main ideas; and only 27% of all paragraphs opened with a directly-stated main idea. Implications for teachers, publishers, and reading researchers are discussed.