classroom experiments using bacteria

A Microbiology Curriculum for K through 12 Grades

(Presented at the 1997 Annual Meeting of the American Society for Microbiology in Miami, FL)

Heather Ewald ('98) and The W&M Curriculum Group
Biology Department
College of William & Mary
P.O.Box 8795
Williamsburg, VA 23187-8795



Approximately 4% of all children entering kindergarten must eventually choose careers in the sciences and technology if future employment demands are to be met. Currently, however, only 2% of the population is entering science-related fields. The greatest rate of attrition in scientific interest occurs before students reach high school.

In order to make science more real and exciting for our students, we propose that microbiology be introduced into the science curriculum as early as kindergarten. We suggest the use of microbiology as no other biological field interfaces so readily with other disciplines. Consider the ties: the impact of disease on history, the use of large numbers, logs and exponentials. Also "micro" can facilitate development of observational skills as well as many of the higher thinking skills in Bloom's Taxonomy. The discussion of everyday issues about health and sociology, the biochemistry and molecular biology revolution can also be initiated through the study of microbiology. We believe that the addition of microbiology will increase interest in science and help head off a personnel deficit in the scientific fields. Furthermore, exposing all students to microbiological concepts at an early age will create a public better educated in many modern issues. They will be better able to understand that many microbes have a positive impact on our lives, and contrast this knowledge with media reports on medical issues such as HIV/AIDS, the rapid spread of diseases in developing countries, and emerging diseases.

Following is a developmental series of curriculum enrichment ideas to aid the introduction of microbiology into existing curriculums.


A Microbiology Curriculum for K through 12 Grades

The following are not meant to be insertions, but rather substitutions so as to add no additional hours to the teachers' already tight time-budget.

We suggest a series of short, 2 to 5 day long modules, one for each semester from kindergarten through high school. Accompanying the laboratory experiments is a list of interdisciplinary connections between microbiology and other units in various areas in the curricula in most schools. What follows is only an example: many other microbiologically related experiments and extensions are possible.

Two laboratory themes begin early dealing with the friendly (non-pathogenic) sides of microbiology: the study of yeast in food preparation, and a botanical trail leading to those marvelous microbial elements called chloroplasts. Along the way students learn that microbes are generally benign, in addition to developing useful skills such as drawing, optical magnification skills, graphing, and dealing with huge numbers, not to mention experimental planning, hypothesizing and observation. This can lead into a study of the natural history of protozoans and algae, and finally into the exploration of bacteria and their viruses. The students encounter a series of developmentally appropriate experiments in which parameters may be varied. As the student advances these fundamental concepts are tested in teh laboratory for their veracity. The implications of these lessons and the research they span can then be discussed in depth and dealt within an interdisciplinary manner in the classroom.

Curriculum Modules for K through High School

LEAF COLLECTIONDiscerning differences and similarities. This botanical experience will be a platform upon which the students will over a period of years build a study of chloroplasts and other 'friendly' prokaryotic organisms.K YEAST-1Baking bread. Yeast makes bubbles in the dough. What is the difference between loaves with and without yeast? What happens if the sugar is left out of the recipe? What happens if the yeast are cooked first?
INTRO TO PLANTSLearning how organisms work. Using dyes to find out how white carnations or celery stalks carry water? Humans are only one of a very few who are tool users. Introduction to optical tools - the magnifying glass.1 YEAST-2Elementary metabolism of this simple microbe will be investigated by the children. The main tools will be balloons connected to bottles, which contain a fermenting yeast suspension. Various amounts of sugar will be added to each bottle and the volume of evolved gas will be estimated by the inflating balloons.
CHLOROPLASTS-1A first look at chloroplasts. Bleaching of the green (chlorosis) by blocking sunlight from leaves for several days. Are the chloroplasts fewer in number or is each one less green? Introduction to tools of slightly higher magnification.2 MICROBIAL ECOLOGY-1Microbes in our local environment. Swabbings will be lifted from various items in the classroom - doorknobs, pencils, coins, desks, hands. Many of these are, surprisingly, self-sterilizing!
CHLOROPLASTS-2Reversal of chlorosis. Previously bleached leaves are re-exposed to sunlight. Observations are made on whether the chloroplasts become more numerous, or does each one become more green. If more numerous, how do they come into being?3 MICROBIAL ECOLOGY-2Human vectors. Sterile agar plates will be opened prior to and after the students arrive in the classroom for the first time in the day.
CHLOROPLASTS-3Photosynthesis. What are these little chloroplasts doing? Elodia is bunched and the middle third of their leaves are wrapped to block light, and they become chlorodic. Later, the leaves are laid horizontally in bright light. Bubbles rise only from the green areas. The gas is collected in inverted tubes and later determined by chemistry to be oxygen.4 MICROBIAL ECOLOGY-3Animal vectors. Ants and other "bugs" will be caught and allowed to walk across various lawns of microbes, and then across sterile petri plates. Discussions then can be done on what flies might be carrying on their feet.
MICROSCOPY-1Using a low-power compound microscope. A number of different small organisms to inspected. Some are eukaryotes (amoeba, daphnia, paramecium, and maybe cheek cells). Others are even smaller - yeast. And yet others are very small - prokaryotic bacteria.5 FOOD MICROBIOLOGYYogurt making. What purpose does each component serve? Why is the temperature kept quite warm? Did you know that yogurt was invented because it was a way to make milk safe when refrigeration and Pasteurization had not yet been invented?
MICROSCOPY-2Symbiosis. A study of the relationship between the prokaryotic and the eukaryotic worlds in lichens. Geological implications are mentioned as a preview to next year's studies in Earth Science.6 BIG NUMBERSExponentials and logarithms. To give a hands-on approach to this mathematical experience, the students will learn how to make plate counts and plot data leading toward a growth curve. Other data can similarly be analyzed: US population growth over the years, corporate growth over the years.
MINERAL CYCLES-1The nitrogen cycle. A study of root nodules in legumes. Growth of beans with and without Rhyzobium.7 MINERAL CYCLES-2Iron, sulfur and natural gas. Can you find any iron bacteria in a local stream near your school? What evidence do you have that sulfur bacteria live in the pond near your school, or in the water pipes in your building? From your geography books, find out where iron and sulfur are mined. How did they get there? Do you think that the pond and stream bacteria might have something to do with making geological deposits. Can you find evidence that natural gas is being made in the bottom of your neighborhood pond?
BACTERIOLOGYAnti-microbial agents. Students will learn how to cultivate bacteria and yeast on petri plates. Then they will test various agents for their inhibitory effects by placing disks, which contain various agents, on the 'lawns' of the bacteria. Tested agents might include penicillin, streptomycin, soap, Listerine, various spices.8 USEFUL TECHNIQUESChromatography and electrophoresis of plant pigments and common enzymes such as catalase (yeast) and a-amylase (saliva).


Most high school students take science for only one year - biology, chemistry, earth science, or physics. With so little time to cover such wide content, we propose only one microbiological experiment be given in either general biology or general chemistry. Students with a more scientific inclination should be encouraged to seek external consultants for projects aimed at science fair or a state level junior academy of sciences.

Health Class: epidemiology - an experiment done in class showing the spread of a "disease" among the students. There are several widely used models for doing this.

Chemistry: the effect of chemical structure on the potency of various antibiotic detergents. A number of quaternary ammonium compounds are available such as Cetavlon-16 versus those with side-chains of 14 and 12 carbons. (Cetavlon = NNNN-trimethyl-hexadecyl-ammonium bromide; common agent in shampoos.)

Chemistry: extraction, concentration and testing of antibiotic compounds found in some spices.

Chemistry: use of yeast for investigating the biochemistry of catalase and its kinetics and inhibitors.

Biology: changing the growth parameters in the production of yogurt: osmotic pressure due to ions versus non-ionic compounds; temperature.


Science Fair and Other Presentations

There is great truth to the statement: "It is not only what you know, but who you know." Good teachers should teach and encourage their students the art of network building. Using these networks, students will easily find summer internships, and return to school in the fall gushing with the excitement of having done something that really matters. Those students who have developed networks and completed internships will find developing science fair and/or junior academy of science presentations relatively easy to do. These internships and presentations will quickly result in those students' becoming accepted into the universities of their choice, and even beyond to graduate or professional schools.

Authors of the curriculum modules:

Heather T. Ewald, Student Coordinator (Education Major with a B.S. degree)

Grades K, 1, 2 and 3:
Leslie Bisbee, Jenny L. Brady, Elizabeth A. Dixon, Tarek El-Sawy, and S. Yumi M. Gazoni.

Grades 4, 5 and 6:
Richard A. Fortunato, John Graham Hardt, Jeffifer R. Lee, Virginia A. Livesay, Stephanie M. Nichols, Carolyn M. Sime, and Erica M. Walsh.

Grades 7 and 8:
Scott A. Boyer, Eric M. Karlins, Czerton E. Lim, Nhien Howard and Jennifer L. Wasyk.

High School:
Josh A. Binder, Elizabeth L. Born, Hamilton B. H. Duong, Elizabeth H. Gillespie, Laurie M. Lenz, C. Cameron McDow, David E. Terry and Edward Scott Tuorinsky.

Carl W. Vermeulen, PhD, faculty mentor.



ART: Enlarging and drawing to scale