Professional writing students must analyze communications in multiple modalities, on page or screen. This project argues that student analysts benefit from using articulated heuristics, summaries of articles, books, or theories in chart form that remain in the visual field with the communication to be analyzed. Keeping the heuristic in view reduces students' cognitive load by narrowing the search for solution to the categories in the heuristic. These heuristics, often one page or one screen, contain key words, phrases, or questions that allow students to approach analysis from experts' points of view at more than one level of complexity. Students locate instantiations of the categories in the communication analyzed, incorporating the category/instantiation pairs into personal schemas for analysis. As students classify communications, relate parts together and to other communications, and perform operations on the content, they see how communication achieves its meaning and formulate appropriate responses. Rather than rely on one all-purpose heuristic, this dissertation presents a range of heuristics reflecting rhetorical, discourse, linguistic, usability, and visual strategies that enable students to critique both form and function in communication. The heuristics reflect a systematically ordered workplace context, articulate an appropriate and specific theory for the situation, interface with other heuristic systems for depth and efficacy, and instantiate the categories at some helpful secondary level of complexity. To theorize the visual nature of the heuristic chart displays, I employ the semiotic of Charles Sanders Peirce, working through the implications of chart construction as I diagram Peirce's theory of diagrammatic iconicity.