Harold Conn developed a way to stain bacteria so scientists could see them under a microscope.  Because bacteria could now be seen he developed rules for classifying them.  He also founded the Biological Stain Commission after World War I.

http://www.twu.edu/dsc/connI.htm

Picture courtesy of the Biological Stain Commission

TEKS Objective References: 

§112.43.c.4.D. (Biology) The student knows that cells are the basic structures of all living things and have specialized parts that perform specific functions, and that viruses are different from cells and have different properties and functions. The student is expected to identify and describe the role of bacteria in maintaining health such as in digestion and in causing diseases such as in streptococcus infections and diphtheria.

Helpful Web sites:

Bacteria Rule!: An Interactive Self-Correcting Game. This is a fun website for kids to browse and learn about bacteria.  It gives them True/False quizzes to test their knowledge. http://www.nationalgeographic.com/ngkids/0010/bacteria/

Teaching Resources:

Staining Bacteria

Milk Experiment: This is a good way to incorporate writing into science activities.  Students can write their observations of the experiment over time in a notebook. You could also use this experiment to teach the scientific method. http://school.discoveryeducation.com/curriculumcenter/bacteria/activity1.html.