"Relationships between concepts, and their contexts, can be more easily and quickly understood using diagrams rather than in textual form," write the authors. This article (19 page PDF) is an exploration of some methods of using diagrams to convey ideas. For example, "The acronym FISh consists of letters representing the 3 stages of the PBL model: Focus – Investigate – Share. Using FISh as the name of the model, the visualisation happens almost automatically as we think about the word 'fish'." The article doesn't cover all types of visual representation, but focuses instead on the sort of planning required to create one.