This on-line collection of exercises can be conducted to illustrate the formation and properties of microbial biofilms. Activities include: A Biofilm Primer, An Interesting Paradox, Build a Biofilm Reactor, Bring 'em Back Alive, Buccal Epithelial Cells & Bacterial Cells: Negative Staining, Buried Slide Technique, Dental Biofilms, Flow Through Gram Stain, Microbial Fishing, Pellicle Formation in a Hay Infusion, Rhizosphere Visualization, Microbial Leaching of Copper Ore, Build a Winogradsky Column, Growth of Dental Plaque in vitro, Biofilms from Soil Crumbs, Vinegar Production and Acetic Acid Titration, Isolation of Azospirillum, Observation of the Formation of Biofilms in a Flowing Environment, Measuring Biofilm Depth.