A Taxonomy Of Graphs

In order to learn the skills of visual literacy, students can practice how to “read” an image. To do this, they need a “language” to understand the different types of graphic tools.

Just as students move up in grade levels, enjoy more complex literature, and solve harder math problems, they also steadily encounter more advanced graphic representations. The skill of graphicacy incorporates clear methods and tools, just as linguistics and mathematics have their own terms and structures.

In their work, “The Development Of A New Taxonomy For Graphicacy” (2009), Xenia Danos and E.W.L. Norman draw upon the work of Edward Fry to offer a new series of classifications for pictorial devices. The authors help teachers introduce graphicacy into their curricula by defining the categories of visual analytics.

For example, in the “Taxonomy of Graphs” (Figure 8), Danos groups different types of displays based on Fry’s descriptions (“Graphical Literacy,” Journal of Reading, February 1981). In the taxonomy, the visual tools become increasingly complex, moving from literal to abstract:

1. Lineal graphs show sequential data, such as story lines, timelines, flow charts, sports playoff brackets, or genealogy charts
2. Quantitative graphs display numerical data, such as line graphs, bar or pie charts, or supply and demand curves
3. Spatial graphs reveal area and location, such as floor plans, road maps, or contour renderings
4. Pictorial graphs rely on visual concepts, such as realistic paintings, cartoons, or abstract drawings
5. Hypothetical graphs address the interrelationship of ideas, such as theoretical models or sentence diagrams
6. Omitted graphs intentionally leave out explanatory details, such as essay outlines, corporate logos, statistical tables, religious symbols, or decorative designs

These vocabularies help teachers describe the steps of visual interpretation to our students. By using a common terminology and understanding which graphs are more or less approachable, we can better help our students use these tools. We can differentiate for each student the appropriate level in graphicacy, just as we level books into reading baskets and move systematically from pre-algebra to algebra to algebra II.