SUMMARY:
In this activity, students explore the contents of untreated water, using a microscope to find organisms, create their own filtering system to clean the water, and then research water-borne pathogens that may be increasing in number due to effects of global warming.

Estimated class time:
2-3 class periods (90 minute blocks)

OBJECTIVES:

Students will:

• Define global warming
• Relate increase in temperature to an increase in potential water-borne pathogens
• Use a microscope to examine water
• Create their own water filtering system
• Research a specific water-borne pathogen
• Display research findings in a poster

MATERIALS NEEDED:

• Sample of fresh water from pond, stream, lake, or other source—the cloudier, the better!
• Microscopes
• Pipettes
• Slides, preferably depression slides
• Assorted substances to use in filters, such as coffee filters, kitty litter, sand, gravel, cotton, cheesecloth
• Funnels
• Beakers
• Guidebooks or textbooks to identify aquatic microorganisms
• Poster boards or construction paper suitable for posters
• Markers, colored pencils
• Internet access
• Other reference materials

PROCEDURES:

Introduction:
Introduce the students to the topic of global warming by directing them to the website "Taking Our Temperature" on this website. Ask what they've heard about global warming and what it might affect. Have them read the "What Is Global Warming" section of this website, and then suggest that global warming may also affect our water supply. Let's take a look at how.

Part I: Observation

1. Provide each pair of students with a sample of water (100 to 150 ml should be sufficient).


2. Students should write a description of the water before doing anything with it.
• How clear is it?
• Is there an odor?
• Any visible substances floating or suspended in the water?
3. Have students use pipettes to drop one drop of water on a microscope slide and then examine it under high power.


4. Students should draw what they see, trying to identify the organisms using texts and guidebooks.

Part II: Filtering

1. Now each group should be challenged to clean up their water. Allow each group to choose small amounts of any three materials from the filter materials supply and design their own filters by layering their chosen materials in a funnel placed over a beaker.
2. Pour water sample through filter
3. Compare the appearance of the filtered water to what it looked like before filtering. Write down observations.
4. Ask students:
• Would you drink the water now?
• Have you removed all the impurities?
• What might still remain in the water?
5. Have students re-examine their water under a microscope to find out which, if any, organisms may have made it through their filters.

Part III: Research

1. Direct students to the page "What's Swimming in Your Glass?" on this website. What questions come to mind after reading the information in the site?
2. Have pairs of students research other organisms found in water that cause disease in humans. Examples include Legionella, Pseudomonas, Klebsiella, Acinetobacter, Aeromonas, Bacillus, Alcaligenes, Moraxella , Giardia, Cryptosporidium, Vibrio cholerae. The following links may be helpful in their research:
• Human Pathogens in Polluted Water
• CDC—Parasitic Disease Information
3. After students have found information about the symptoms, specific pathogen, transmission, occurrence, and treatments for their particular disease, they should create a "Wanted Poster" for that pathogen which displays their research findings.


4. Have students include a statement on their posters that indicates how some of these diseases might be on the rise, due to global warming.


5. Students can then present and display their posters.

ASSESSMENT:

• Techniques, observations and drawings from the water examination and filtering lab.
• Poster
• Presentation
• Participation in discussions, lab activities, research

EXTENSION ACTIVITIES:

• Research where in the world their diseases are occurring most frequently and create a map to display.
• Investigate local water treatment plants for information on how they prevent water-borne pathogens.

RELEVANT CURRICULUM STANDARDS:
This lesson correlates to the following National Science Education Standards, located online at bob.nap.edu/html/nses/html/6e.html#csc912, and National Health Education Standards located online at www.aahperd.org/aahe/pdf_files/standards.pdf.

National Science Education Standards

Content Standard F:
As a result of activities in grades 5-8, all students should develop understanding of:

Natural and human-induced hazards

• Human activities can enhance potential for hazards. Acquisition of resources, urban growth, and waste disposal can accelerate rates of natural change.

As a result of activities in grades 9-12, all students should develop understanding of:

Personal and community health

• The severity of disease symptoms is dependent on many factors, such as human resistance and the virulence of the disease-producing organism. Many diseases can be prevented, controlled, or cured.

Natural resources

• Human populations use resources in the environment in order to maintain and improve their existence. Natural resources have been and will continue to be used to maintain human populations.

Natural and human-induced hazards

• Human activities can enhance potential for hazards. Acquisition of resources, urban growth, and waste disposal can accelerate rates of natural change.

National Health Standards

Health Education Standard 1:
Students will comprehend concepts related to health promotion and disease prevention by:

• analyzing how environment and personal health are interrelated.
• describing how lifestyle, pathogens, family history, and other risk factors are related to the cause or prevention of disease and other health problems.
• analyzing how the prevention and control of health problems are influenced by research and medical advances.

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