Teaching GIS is relatively simple, a matter of helping students develop familiarity with the software. Mapping as an aid to thinking is harder to instruct. This article presents a laboratory and lecture package developed to teach the utility of mapping in a course on spatial data analysis. Following a historical review of the use of surface mapping in medicine, it investigates a recent outbreak of salmonella. The lab teaches two different analytic techniques, hierarchical buffers and a surface kerneling approach. The result is a historically grounded program in which different means of address are compared and considered by students. (Contains 7 figures and 1 note.)