Classroom instruction varies among high school academic departments. To understand how instruction in core subjects can differ, an awareness of the two axes that define instruction is required. In this article, the author discuss the two axes, namely, knowledge-versus-skill axis and level of mental engagement axis, that help describe what instruction should look like in each core subject. The knowledge-versus-skill axis examines whether students are expected to learn a body of knowledge about a subject or acquire skills related to that subject. The second axis concerns the level of mental engagement that students experience in a class lesson and is related to Bloom's taxonomy (Bloom, 1956). The level of engagement in the context of a lesson depends on whether students are asked to engage in lower level cognitive functions--such as recalling data, listing, describing, or identifying--or higher level cognitive functions such as evaluating, judging, analyzing, or synthesizing information. Understanding the two axes that define instruction makes it easier to describe how classroom instruction between high school academic departments can vary. The authors also discuss a two-step process the teachers must use for students to learn and offer steps the administrators can take to be good practitioners. (Contains 2 figures.)