In an introductory lesson, youngsters take a pre-assessment quiz, get a grasp of a gram of mass, and then estimate the mass of microorganisms that live within a human body. Using Glo Germ™, a material that allows you to simulate the passing of germs by hands, mini microbiologists get an ultraviolet view of the importance of hand washing. To close, small groups construct a concept map of what they have learned, one that will be added to throughout the unit. A wonderful kick-start to a unit that is a whole new world!