Visual rhetoric can be presented to students as a language, a set of codes and cues that work together to create meaning and make arguments. In this sense, visual rhetoric is a lot like traditional rhetoric, providing its own "vocabulary" that will enable an author to make appeals to the viewer's reason, emotions, and values—or ethos, pathos and logos.
Rather than working with the subtleties of diction and phrasing (though words can certainly be part of a visual appeal) visual rhetoric calls upon a whole different set of systems. Color, composition, image content, and even typeface can be manipulated to provoke a response from a viewer, and tap into deep wells of personal and cultural meaning, experience, and emotion. In addition to the graphic and symbolic vocabularies that make visual rhetoric so powerful, images can also contain implied narratives. In reconstructing the narrative implied in, for example, a prescription drug ad, the viewer participates in the construction of meaning. Visual rhetoric thus relies upon the viewer's ability to respond both consciously and unconsciously to graphics and images, and the arguments they create.
Here are some links that further address the concepts behind visual rhetoric and suggest ways the concepts can be applied in the classroom: