The problem is, however, it’s a tool of limited use. Once you get beyond three sets, especially three complicated sets, it’s hard to show relationships clearly.

However, the diagram itself is unlikely to have direct practical applications. “We use two and three-set Venn diagrams for working out simple logical puzzles,” Cameron says.

This paper describes the use of a three-circle Venn diagram as a vehicle for introducing pre-service elementary teachers to pedagogical content knowledge (PCK). Each circle of the diagram represents ...