Human Venn diagram

This is a good activity for teaching how Boolean operators work.  Give the class statements like "people who like cats AND dogs" and "people who like cats OR dogs."  Have them stand up if they fit the description.  In this example, the first one would have only people who like both animals standing up, and the second would have anyone who likes either animal standing.  It helps to make the way Boolean operators work more clear by giving a clear visual of what the results are like when different operators are used.