TITLE: BACTERIA
AUTHOR: JIM L. TORGERSON, NORTH SEVIER MIDDLE
SCHOOL, SALINA, UTAH
GRADE LEVEL: Appropriate for grades 6-8.
OVERVIEW: The students will be able to describe
bacteria as it relates to them.
PURPOSE: By gaining an understanding of bacteria,
students will have the knowledge to deal with bacteria,
their advantages and disadvantages.
OBJECTIVE(s): STUDENTS WILL BE ABLE TO:
1. Tell what a bacteria is.
2. Draw and label the types of bacteria.
3. Explain how different bacteria can affect them.
4. Understand bacteria relationships to their
environment.
BACKGROUND INFORMATION:
Bacteria are one-celled organisms. Bacteria are
the smallest organisms that are clearly alive. The
three major types of bacteria are cocci, bacilli, and
spirilla. Bacteria need food, water, and a suitable
temperature in which to live. Some bacteria cause
disease, while others are not harmful. Some bacteria
help in the reduction of plant and animal waste to soil
nutrients; others are used in the production of cheese.
RESOURCES/MATERIALS:
RESOURCES: LIFE SCIENCE TEXT BOOK, BIOLOGY TEXT
BOOKS, ENCYCLOPEDIA, ANY OTHER RESOURCES THAT RELATE TO
BACTERIA THAT ARE AVAILABLE.
You will need to start with pictures and/or
drawings of the different types of bacteria. The
students need to have a basic understanding of bacteria
before you start the activity. Hold a short discussion
about bacteria.
You will need the following materials:
1. microscope (and knowledge of how to use)
2. prepared slides of bacteria
3. incubator
4. sterile petri dishes
5. nutrient agar
6. paper and pencil for notes.
Disposable or nondisposable petri dishes can be
obtained from biological supply companies.
Make sure students have had experience labeling
types of bacteria before starting this activity.
CAUTION: BE SURE THE PETRI DISHES REMAIN SEALED WITH
TAPE AND THEY ARE DISPOSED OF PROPERLY FOLLOWING THIS
ACTIVITY.
Also, this activity will take a few minutes each
day for several days to complete.
ACTIVITIES AND PROCEDURES:
Give each student a prepared sterile petri dish
(one that already contains the growing media nutrient
agar). MAKE SURE STUDENTS DO NOT OPEN THE DISH UNTIL
THEY ARE READY TO EXPOSE IT. Have students expose
their dish to any environmental conditions they can
think of: i.e., chalk dust, leaves, saliva, dead
flies, grass, soil, dirty hands, water, etc. I usually
save two dishes for my use: One dish is for the
control (just tape it shut without exposure). The
second dish I have someone in the class kiss it to show
bacteria growth of bacteria that come off the lips. It
is important that students do not put too much stuff in
the petri dish. Limit to two very small substances,
one on each side of the dish. After the students
inoculate (expose) their dish they need to take notes
on time of exposure and what the agar was exposed to.
Students need to put their name on a "small" piece of
masking tape, taped off to one side of their specimen.
The student needs to give the dish to the teacher. The
teacher needs to tape the dish shut. The exposed petri
dish can now be put in the incubator. Set the
incubator around body temperature. Don"t forget to add
a little water in the bottom of the incubator to keep
the humidity up.
IT IS IMPORTANT THE DISH REMAINS SEALED FROM THIS POINT
ON- MAKE SURE STUDENTS DO NOT TURN THE DISH UPSIDE DOWN
WHEN YOU HAND THEM BACK FOR OBSERVATIONS UNLESS THEY
ARE FAIRLY DRY CULTURES.
24 Hours later hand out each student their petri
dish. (It is important you don't start this activity
on a Friday) Each person needs to record observations
of their dish. When finished put dishes back in the
incubator.
48 hours later (from initial exposure) hand out
each student their petri dish for more observations.
Don't forget to hand out the control dish. When
finished put the dishes back in the incubator. 72
hours later (from initial exposure) hand out the petri
dishes for the last time. Have students take their
final observations and after a class discussion make
some conclusions. Now you are ready to relate and
review bacteria types to the bacteria cultures they
have in their petri dish. You may want to wait for a
full class period to do the microscope work. Hand each
student a prepared slide containing the bacteria types.
(Some schools will have the necessary equipment to make
and stain their own slides off the bacteria the
students have cultured. Please do not try to do this
unless you have had the proper training in preparing
bacteria mounts due to the disease potential from
pathogens). Put the slide on the microscope stage.
Focus the microscope, using the techniques discussed in
a previous lesson. Have students draw on a piece of
paper what bacteria types they are able to see. Have
students identify the bacteria they are drawing. Have
students use reference sources to identify and label
the bacteria being viewed. After the lab, discuss the
advantages and disadvantages of bacteria (i.e.,
bacteria diseases, decomposition of organic material,
etc.) This will probably be done in another class
period. Also discuss how bacteria affect their
environment.
TYING IT ALL TOGETHER:
CROSS-CURRICULUM IDEAS:
Math: Have students conduct a poll to determine if
people consider bacteria helpful or harmful. Tally the
records and make graphs for the subgroups polled such
as: elementary students, teens, high school students,
parents, and grandparents.
English: Have students compose a story about the
thoughts of a plant or animal that lives in an
environment where there are no decomposers. They could
describe the anguish about rising level of waste, etc.
Art: Draw and color bacteria as you would see them in
their natural surroundings.
Health: Identify and discuss ten health practices that
deal with illness or health. i.e.; food poisoning.
History: Have students research the historical effects
of major diseases. Some diseases might be bubonic
plaque, polio, influenza, malaria, cholera, scurvy,
smallpox, etc.
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John Kurilecjmk@ofcn.org