# Showing the Overlap with Venn Diagrams

Venn diagrams are another way to show how something is split up, but it is designed to work for the things being described can have more than one characteristic at a time. An easy example is a survey of a junior high school classroom to find out which students have a computer at home and which have a bicycle at home. In a classroom of 40 students, let us imagine that 15 say they have computers and 20 say they have bicycles. A single student can be characterized as "having a bicycle," as "having a computer," as "having both," or as "having neither." In other words, there are two categories of "having" and each student is classified as "yes" or "no" in each category. We need some visual way to show who has what. In a Venn diagram, we draw a "blob" to show all the students who have bicycles, and then we draw another "blob" to show all the students who have computers – but the interesting part is whether that second blob is completely separate from the first blob, overlapping some, or completely overlapping. Venn diagrams give a visual description of how many students are in the category of "having both."