Remember Venn diagrams?
Useful tools in explaining relationships among sets of things. I use them a lot in Statistics, particularly in analyzing probabilities. And I’m surprised (as I often am) by my students’ unfamiliarity and discomfort with yet another basic mathematical tool (as usual I blame the emphasis on TAKS testing!)
But here’s a report on the exotic world of the Venn diagram and the search for the beautiful, symmetric Venn diagram as you involve more and more sets. Here’s what a five set Venn looks like:

It seems research has determined that it takes a prime number of sets to be capable of producing a symmetrical Venn diagram. Here’s the seven-set version:

And now comes the first Venn diagram for 11 sets – extra credit for labeling all sections!