In order to examine the value of explicating genre and rhetorical rules for teaching, this study explores the level of consistency between the linear, deductive discourse pattern recommended for school writing and the actual structure of reading materials selected from seventh- and eighth-grade English language arts textbooks. We focus on 25 opinion or thesis-driven essays selected from Canadian and US textbooks to (1) identify the general discourse patterns and (2) determine if the main idea is presented in the introduction. We found that these texts all have a three-part structure consisting of introduction, body, and conclusion. However, the introductions in some texts are lengthy with multiple paragraphs. In addition, the opinion or main idea is not necessarily presented in the introduction but rather in the middle or at the end of the essay. The finding of a gap between the pattern recommended for school writing and the actual structures that appear in some of the reading materials in school textbooks highlights the problem of explicating discursively constructed rhetorical conventions in teaching.