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6-8 > Microscopic World
Grade level: 6-8 Subject: Microscopic World Duration: Two class periods
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Objectives | Materials | Procedures | Adaptations | Discussion Questions | Evaluation | Extensions | Suggested Readings | Links | Vocabulary | Academic Standards | Credit
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Objectives
 



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Fighting Invisible Enemies




Students will understand the following:
1. Before the discovery of antibiotics, many more people died or were disabled by diseases that are now curable.
2. Antibiotics fight diseases that are caused by bacteria.
3. Bacteria are microscopic organisms, invisible to the unaided eye, that are constantly changing and developing antibiotic-resistant strains.
4. We need new antibiotics that can fight resistant strains of bacteria, but we also need to control the development of antibiotic-resistant bacteria by using antibiotics carefully.
Materials

For this lesson, you will need:
Research materials about bacteria and antibiotics
Computer with Internet access
Procedures

1. Initiate a discussion with your class about illness, medical treatment, and medication. Encourage students to discuss times when they’ve been ill enough to need medical care. What sorts of treatment did they receive? What kinds of medication were they given?
2. Continue the discussion by asking if any students have taken antibiotic medication. If so, for what illnesses? What were the instructions for taking the antibiotics? (Students should note that antibiotics are prescribed as a course, so that patients take them a given number of times per day for a typical period of 10 days or more.)
3. Go on to talk about what happened before antibiotics were available. Lead students to realize that before antibiotics, many people died or were disabled by diseases that are now curable, or no longer exist.
4. Divide your class into small research groups, assigning each group one of the following topics to research in the library, on the Internet, or using the materials you have provided:
Bubonic plague
Antibiotics
Pneumococcus
Pneumonia
Meningitis
Penicillin
Virus
5. When individuals in a group have completed their research, have them work together as a group to prepare written reports on their findings.
6. Invite students to share their reports with the class as a whole.
7. If none of the reports have touched on bacteria that have developed antibiotic-resistant strains, raise the topic with the class now. If the subject has come up in one or more reports, direct students’ attention to that subject. Talk about why bacteria become resistant to antibiotics. Students should understand that when a person takes an antibiotic, the bacteria in her or his body mutate, or change, so that they can survive the antibiotic. Then the mutated bacteria are passed on to others.
8. Lead students to understand further that although it is important that researchers develop new antibiotics to fight resistant bacteria, we can also control the trend toward antibiotic resistance in the following ways:
  1. Do not insist on receiving antibiotic treatment for illnesses that your doctor feels your own immune system can combat.
  2. Take antibiotics properly when they are prescribed. The proper way to take antibiotics is to take the entire course, rather than stopping when symptoms are alleviated. Taking only a few doses of the medication and not completing the course encourages the development of resistant bacteria.
  3. Since viruses are not affected by antibiotics, no one should take antibiotic medication until it is established that he or she has a bacterial infection rather than a viral infection.
  4. No one should stockpile unused antibiotics and then self-prescribe the medication later on without the advice of a doctor.
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Adaptations

Adaptations for Older Students:
Have students do research to discover how penicillin and other antibiotics work to destroy bacteria.
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Discussion Questions

1. In recent years, we have witnessed an increase in the number of serious infections. Relate what you know about how young children interact and how infectious diseases and drug-resistant diseases are spreading. What types of situations would maximize the spread of disease?
2. Describe how Dr. Ryder utilized the scientific method to track the breeding habits of the aegypti mosquito.
3. Discuss what methods of mosquito control would be most useful given the information on habitat, life cycle, and the experimental results of the breeding behavior of aegypties.
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Evaluation

You can evaluate your students on their reports using the following three-point rubric:

  • Three points:reports clear, complete, well organized, and error-free

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  • Two points:reports fairly clear, sufficiently well organized, with some errors

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  • One point:reports sketchy and vague, poorly organized, with numerous errors
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Extensions

Scales of Life
Using balloons, modeling clay, or other materials, make models of bacteria, viruses, and other disease-causing microbes (protists). Relate their scale size in your models.

Taking Aim
Make a diagram of a bacterium, labeling the major structures. Below it make a list of various antibiotics used to treat bacteria. Include the name of the antibiotic and the bacterial structure it targets. For example: penicillin, bacterial membrane.

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Suggested Readings

"The Bubonic Plague"
Colin McEvedy, Scientific American, February 1988
The Bubonic Plague, a bacterial terror in a time before antibiotics, decimated the populations of Europe and Asia during the Middle Ages.

"Beating Bacteria"
Sasha Nrmecek, Scientific American, February 1997
Bacteria's ability to grow resistant to drugs has renewed the threat of some common diseases. Scientists are meeting the challenge with innovative new antibiotics.

"Mosquitos, the Mighty Killers"
Lewis T. Nielsen, National Geographic, September 1979
Mosquitos pollinate plants and provide food for birds, fish, and other creatures. Yet this airborne annoyance results in more human death and sickness than any other animal.

"The Specter of Biological Weapons"
Leonard A. Cole, Scientific American, December 1996
The recent use of deadly bacteria, viruses, and nerve gases by terrorists has raised the need for an international ban on chemical and biological weapons.

When Plague Strikes: The Black Death, Smallpox, AIDS
James Giblin, HarperCollins, 1995
The histories of several devastating diseases and the search for their cures are covered especially for young people in this work.

The Magic School Bus Inside Ralphie
Hasmi Giankoumis, Lawrence Jacobs & Jocelyn Stevenson, Scholastic, 1994
Junior high school students will enjoy this video which features an animated tour of the inside of the body of a sick youngster to see both the bacteria and the operations of the immune system to defeat the bacteria.

The Race Against Lethal Microbes
A Report from the Howard Hughes Medical Institute, 1996
This booklet chronicles the battles of science against infectious diseases, including new drug-resistant strains of tuberculosis, malaria, and pneumonia, and of course, AIDS.

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Links

Bed Bugs


Microbe Zoo - The Digital Learning Center for Microbial Ecology


Small Things: What Lives in Pond Water?


Scanning Electron Microscope


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Vocabulary

Click on any of the vocabulary words below to hear them pronounced and used in a sentence.

speaker    plague
Definition:An epidemic disease causing a high rate of mortality.
Context:The plague wiped out a third of Europe's population in the 1700s.

speaker    antibiotic
Definition:A substance produced or derived from certain fungi, bacteria, and other organisms that can destroy or inhibit the growth of other microorganisms, and is widely used in the prevention and treatment of infectious diseases.
Context:Even simple bacterial infections were fatal until antibiotics were developed, but the power of antibiotics is fading.

speaker    pneumococcus
Definition:A bacterium (Streptococcus pneumoniae) that causes an acute pneumonia involving one or more lobes of the lung.
Context:This is the culprit or pneumococcus bacterium. All kids carry these bugs. They not only cause ear and sinus infections, but also life-threatening blood infections, meningitis, and pneumonia, and new drug resistant strains are difficult to treat.

speaker    bacteria
Definition:A group of prokaryotic unicellular round, spiral, or rod-shaped single-celled microorganisms that are often aggregated into colonies or motile by means of flagella, that live in soil, water, organic matter, or the bodies of plants and animals, and important because of their biochemical effects and pathogenicity.
Context:Bacteria are the Earth's most ancient and numerous creatures. Their ancestors first appeared three-and-a-half billion years ago.

speaker    pneumococcus meningitis
Definition:A disease caused by the Pneumococcus bacterium in which inflammation of the meninges occurs.
Context:Pneumococcus meningitis is a serious brain and spinal cord infection; the damage can be extensive fairly early on.

speaker    white blood cells
Definition:Cells normally present in blood which act as defenders against invading bacteria and viruses.
Context:In serious infections, white blood cells are overwhelmed and many die.

speaker    penicillin
Definition:Any of several relatively nontoxic antibiotic acids that are produced by molds or synthetically and are used especially against cocci.
Context:Penicillin, for example, causes bacteria to burst without harming human cells at all--the perfect magic bullet until recently.

speaker    malaria
Definition:A human disease that is caused by sporozoan parasites (genus Plasmodium) in the red blood cells, is transmitted by the bite of anopheline mosquitoes, and is characterized by periodic attacks of chills and fever.
Context:Malaria, a disease spread by mosquitos, kills more than two million people every year.

speaker    Dengue fever
Definition:An acute infectious disease caused by an arbovirus, transmitted by aedes mosquitoes, and characterized by headache, severe joint pain, and a rash--also called breakbone fever.
Context:Dengue fever, a painful tropical disease that can be lethal.

speaker    aegypties
Definition:A type of mosquito with females that have a set of slender organs in the proboscis adapted to puncture the skin of animals and to suck their blood and that are in some cases vectors of serious diseases.
Context:Dengue-carrying aegypties lay their eggs close to water, where they rest until a rainfall occurs.

speaker    larvae
Definition:The immature, wingless, and often wormlike feeding form that hatches from the egg of many insects, alters chiefly in size while passing through several molts, and is finally transformed into a pupa or chrysalis from which the adult emerges.
Context:When they (aegypties) are flooded, they begin to develop. Within a few days they hatch into larvae.

speaker    pupae
Definition:An intermediate, usually quiescent stage of a metamorphic insect (as a bee, moth, or beetle) that occurs between the larva and the imago, is usually enclosed in a cocoon or protective covering, and undergoes internal changes by which larval structures are replaced by those typical of the imago.
Context:Within a week they (aegypties) develop into pupae, the stage at which they change from aquatic creatures into airborne insects.

speaker    rubidium
Definition:A soft, silvery metallic element of the alkali metal group that reacts violently with water and bursts into flame spontaneously in air.
Context:It's laced with rubidium, a trace metal that the mosquitos then leave behind in their eggs.

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Standards

This lesson plan may be used to address the academic standards listed below. These standards are drawn from Content Knowledge: A Compendium of Standards and Benchmarks for K-12 Education: 2nd Edition and have been provided courtesy of theMid-continent Research for Education and Learningin Aurora, Colorado.
 
Grade level:9-12
Subject area:life science
Standard:
Knows the general structure and functions of cells in organisms.
Benchmarks:
Knows that most cell functions involve chemical reactions; food molecules taken into cells are broken down to provide the chemical constituents needed to synthesize other molecules; both breakdown and synthesis are made possible by a large set of protein catalysts called enzymes.

Grade level:9-12
Subject area:life science
Standard:
Knows the general structure and functions of cells in organisms.
Benchmarks:
Knows that every cell is covered by a membrane that separates it from the outside world and controls what molecules can enter and leave the cell; in all but quite primitive cells, a complex network of proteins provides organization and shape and, for animal cells, movement.

Grade level:9-12
Subject area:life science
Standard:
Understands the genetic basis for the transfer of biological characteristics from one generation to the next.
Benchmarks:
Knows that genes are segments of DNA molecules, and that inserting, deleting or substituting portions of the DNA can alter genes; changes in DNA (mutations) can also occur when a cell is exposed to certain kinds of radiation or chemical substances.

Grade level:9-12
Subject area:life science
Standard:
Knows about the diversity and unity that characterize life.
Benchmarks:
Knows that the variation of organisms within a species increases the likelihood that at least some members of the species will survive under changed environmental conditions, and a great diversity of species increases the chance that at least some living things will survive in the face of large changes in the environment.

Grade level:9-12
Subject area:life science
Standard:
Understands how species depend on one another and on the environment for survival.
Benchmarks:
Knows that organisms both cooperate and compete in ecosystems; the interrelationships and interdependencies of these organisms may generate ecosystems that are stable for hundreds or thousands of years.

Grade level:9-12
Subject area:life science
Standard:
Understands how species depend on one another and on the environment for survival.
Benchmarks:
Knows that humans are increasingly modifying ecosystems as a result of population growth, technology and consumption; human destruction of habitats through direct harvesting, pollution, atmospheric changes and other factors is threatening global stability, and if not addressed, ecosystems will be irreversibly damaged.

Grade level:9-12
Subject area:technology
Standard:
Understands the nature of scientific knowledge.
Benchmarks:
Knows that because all scientific ideas depend on experimental and observational confirmation, all scientific knowledge is, in principle, subject to change as new evidence becomes available; in areas where data, information or understanding is incomplete, it is normal for scientific ideas to be incomplete, but this is also where the opportunity for making advances may be greatest.

Grade level:9-12
Subject area:technology
Standard:
Understands the nature of scientific inquiry.
Benchmarks:
Knows that results of scientific inquiry new knowledge and methods emerge from different types of investigations and public communication among scientists; the nature of communicating and defending the results of scientific inquiry is guided by criteria of being logical and empirical and by connections between natural phenomena, investigations and the historical body of scientific knowledge.

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Credit

Louise Roy Fowler, science teacher, Oakcrest School, Washington, D.C.
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