The Kirby-Bauer antimicrobial susceptibility test can be modified to provide students the opportunity for enhanced learning by comparing their data and discussing the ramifications of their results. The active learning helps students to identify and correct several common misconceptions. The misconceptions addressed include: that the particular organism they tested will give invariable results, that any culture of a species is identical to other cultures of that species, that differences in technique will not be reflected in the experimental results, and that sensitivity testing is not a necessary adjunct to appropriate treatment.