The activity was designed (for seniors) to demonstrate the diversity of the oral flora and to enable discovery of some of the difficulties associated with sampling, cultivation, isolation, and identification of biofilms. By comparing the yield and nature of the microorganisms isolated from plaque and toothbrushes under specified conditions, conclusions can be drawn as to the contamination of an inert fomite (the toothbrush) with a dynamic ecological entity (dental plaque). Dental plaque is an excellent example of a rich diverse biofilm, and this activity provides the student with an opportunity to uncover this biological complexity.The exercise may be carried out as an individual or group activity. Time management, report writing, data analysis and presentation are also important aspects of the exercise.