In teaching middle school students about diseases and microbes, it is surprising to discover how little they know about transmission. Misconceptions range from the idea that "giving a disease to someone" actually means "giving it away so you didn't have it anymore yourself" to a lack of understanding that tiny living things, and not dirt, are generally the cause of illness. This article describes a unit that would teach students about the microbes in their world with an emphasis on those that cause sickness. Anything that might be considered "disgusting" (and that includes gastrointestinal illness) generally appeals to middle school students. Additionally, this activity was designed to introduce students to careers in epidemiology by allowing them to investigate an outbreak themselves. (Contains 3 figures.)