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Activity Guide
Troubled Waters: The F-Files


  • Incorporate live animal presentations
  • Suggest the research component as in-class follow up
  • Look for connections to exhibits in which scientific research is reported
  • Develop the content into a theatrical presentation
  • Combine with local field investigations. Check www.scorecard.org to search by zip code for information on local environmental issues


Explore the connection between toxic chemicals and living things as you read a comic strip about an investigation of frogs in Minnesota.


Students will:

  • Explain some of the ways biodiversity can be affected by toxic chemicals and other environmental threats.
  • Research environmental health topics using books, journals, interviews, and the Internet.
  • Produce a summary and position statement on an environmental, health-related research topic.


Science, Social Studies


ecotoxicology, pesticide, environmental health, fertility, global warming, hormones, indicator species, infertility


2 sessions, plus research time



This activity supports the following National Academy of Sciences Science Education Standards (Grades 5-8):

  • Unifying Concepts and Processes—Evidence, models, and explanation
  • Unifying Concepts and Processes—Constancy, change, and measurement
  • Unifying Concepts and Processes—Evolution and equilibrium
  • Standard A: Science as Inquiry—Abilities necessary to do scientific inquiry
  • Standard A: Science as Inquiry—Understanding about scientific inquiry
  • Standard C: Life Science—Structure and function in living systems
  • Standard C: Life Science—Reproduction and heredity
  • Standard C: Life Science—Regulation and behavior
  • Standard C: Life Science—Populations and ecosystems
  • Standard C: Life Science—Diversity and adaptations of organisms
  • Standard D: Earth and Space Science- Structure of the earth system
  • Standard F: Science in Personal and Social Perspectives—Populations, resources, and environments
  • Standard F: Science in Personal and Social Perspectives—Natural hazards
  • Standard F: Science in Personal and Social Perspectives—Risks and benefits
  • Standard F: Science in Personal and Social Perspectives—Science and technology in society
  • Standard G: Science in Personal and Social Perspectives—Science as human endeavor
  • Standard G: Science in Personal and Social Perspectives—Nature of Science


In August 1995, a Minnesota middle school class took a field trip to a farm in the south-central part of the state. While hiking, the students tried to catch the frogs that they saw on the trail. One of the students caught a frog with only one leg. Other students caught frogs with deformed legs, eyes, and other parts. In fact, half the frogs they caught had some kind of deformity.

Because of what the students found that day, people began investigating the frogs in that area. Since 1995 there have been high rates of physical deformity in frogs found not only in Minnesota but in many other states as well. In fact, there have been deformed amphibian findings in many parts of the world. No one knows exactly what is causing the deformities. But many scientists believe the frogs are being affected by contamination of the air, water, and/or soil. These researchers wonder: If frogs are being affected now, could humans be next?

The connection between environmental health and human health is a new, complex area of study called ecotoxicology. Your students may be familiar with some environmental health issues that have received a lot of media attention — for example, the link between air pollution and respiratory problems, or the links between ozone depletion, increased UV radiation, and skin cancer. But your students might not know about the wide variety of environmental concerns — everything from global warming to pesticide use to household chemicals — that scientists are researching today to find out about their effects on human health. The frogs in Minnesota show that humans are not the only ones whose health may be affected by changes in the environment. Some scientists think other species of animals and plants are even more vulnerable than humans. But what creates health problems for wildlife could very well create health problems for humans, and vice versa. In addition, since living things are connected in the web of life, if one species declines because of environmental contamination, the effects are likely to be felt by many other species in the ecosystem.

The field of ecotoxicology presents more questions than answers. This activity is designed to guide your students on an open-ended investigation of environmental health topics. Introduce them to the F-Files, then set them off to find out what is happening with the health of frogs, people, and lots of other creatures across the planet.


1. Make copies of The F-Files comic strip , keeping the two parts on separate sheets of paper. Hand out only the first page at the beginning of the activity. Then hand out copies of the second page halfway through the activity.

2. Make copies of Get on Your Case! for each team.


1. Pass out the first page of The F-Files comic strip. Tell the students that the comic strip you are passing out is based on a real unsolved mystery. Have them read it to themselves. Then ask one or two volunteers to summarize what Agents Croaky and Hopper of the Bureau of Scientific Investigation (BSI) are investigating.

2. Ask students the following Questions for the Class. Be sure to let the students know that there is no single correct answer to any of the questions. Record their suggested answers on the board.

Questions for the Class

a. If you were Croaky and Hopper, what sorts of questions would you ask in order to begin your investigation? (Answers may include the following: When did the changes begin? What other changes related to the environment or human activity occurred at that time? Have changes occurred in other types of animals?)

b. If you were Croaky and Hopper, where would you begin looking for clues to solve this mystery? What would you ask a laboratory team at headquarters to analyze? (Answers. Check contaminant levels in the air, water, and soil-samples checked against records of historical data may show changes in air and water quality and contamination in the soil-check for contaminant levels in the frogs themselves; look for high densities of parasites in the water; and so on.)

c. How might the problems with the frogs affect other plants and animals? (Answer: The problems affecting the frogs could be affecting both the animals that eat the frogs and whatever the frogs eat; the problems affecting the frogs could be affecting other species, too, and so on.)

3. Pass out the second page of The F-Files comic strip, and have the students read it. After the students have finished, discuss the comic strip. Ask the students if the scientists at the Bureau of Scientific Investigation agreed on the cause of the frog deformities. What were some of the different explanations the scientists provided? Did all of the theories sound equally credible? Which explanations sounded most likely? Why?

Encourage the students to follow their hunches when choosing a theory that sounds the most plausible. Also point out that it is important to evaluate the sources of the scientists’ information. International Tabloid, for example, does not sound like a credible journal. Explain to the students that whenever they hear conflicting information about a topic, they should find out the sources of the information and assess how well respected those sources are.

4. Introduce the topic of environmental health. Explain to the students that the investigation of frog deformities is one of many areas of research in which scientists are looking at possible connections between environmental changes and the health of wildlife, plants, and humans. Ask the students if any of them can name illnesses that are thought to be tied to environmental problems. If you need to jump-start students’ thinking, suggest that they consider such conditions as asthma, cancer, and birth defects. Then ask students to think about how these illnesses may be connected to environmental quality. As students name connections, ask them if they know whether the links are proven or suspected. Where did they get their information?

5. Pass out copies of Get on Your Case! Tell the students that there are many things scientists still do not know about the links between the state of the environment and the health of living things. But there are a lot of ideas out there — some more fully researched than others. Explain that you have passed out a list of topics that are currently being investigated by people all over the world. Using magazines, newspapers, books, and the Internet, the students’ job is to try to collect as much information as they can on one of the topics. Remind them to look hard at the credibility of their sources. They will need to be especially careful to scrutinize Web sites — even a site with an official-sounding name might be nothing more than one amateur’s unsubstantiated ideas.

Organize the class into teams of two or three students. Then allow each team to pick one of the topics. More than one team can pursue the same topic, but encourage the teams to investigate as many of the alternatives as possible. Explain that they should do their best to answer the questions listed under their case descriptions.

Give the students several days in class or after school to conduct their research. They should use the school’s library and computer lab (for Internet access) for information. Encourage students to illustrate their research with graphs, charts, maps, and other visual resources, as scientists and geographers do, to make concepts easier to understand. This not only adds a bit more challenge to the students but also makes their presentations more interesting.

6. Have a group reporting session. When the students have finished their investigations, have them share their results with the class. Each team should describe the topic it investigated, explain the research methods it used, and describe the results of its research.

7. Discuss connections. Afterward, see if any teams can name connections between their area of study and that of one or more of the other teams. As they cite connections, have the students keep a list of the relationships, or, if possible, record a complete web of interrelationships on the board. Finish the discussion by asking the students if they have any final reflections on their investigations. You may want to re-emphasize that there are many complex interrelationships among living things as well as between living things and the physical environment.


The students’ reports should serve as one means of assessment. In addition, interview the students, individually or in groups, asking the following questions about their reports. (You can also have them write answers to the questions.)

a. How did you conduct your search for information?

b. Which sources were the most valuable and why?

c. What were indicators of bias in the materials you examined?

Needs improvement—The student cannot adequately answer the questions.

Satisfactory—The student is able to address each question on a satisfactory level.

Excellent—The student is able to fully address the questions and provide in-depth answers.


  • Have the students turn their own investigation into a comic strip that is in The F-Files style. They should feel free to turn themselves into fictional investigators and play up the dramatic elements of their research.
  • Have your students conduct their own amphibian survey to monitor amphibian deformities in your area. They can visit the North American Amphibian Monitoring Program Web site at www.pwrc.usgs.gov/naamp/. They can also visit the North American Reporting Center for Amphibian Malformations at frogweb.nbii.gov/narcam/.
  • In many areas, poor communities are sometimes exposed to more environmental health risks than their more affluent neighbors. Have students research environmental justice issues and write a short case study that highlights one example of the link between poverty and environmental health factors.


Visit the Center for Global Environmental Education Web site, “A Thousand Friends of Frogs,” at www.cgee.hamline.edu/FROGS/index.htm .

Visit the Frog Web site at www.frogweb.gov .

Visit the Minnesota New Country School Frog Project Web site at mncs.k12.mn.us/frog/ .

Visit the Minnesota Pollution Control Agency Web site at www.pca.state.mn.us/hot/frogs.html .

Visit the North American Reporting Center for Amphibian Malformations Web site at frogweb.nbii.gov/narcam/ .

Books, Articles, and Videos

  • Biodiversity! Exploring the Web of Life Education Kit by World Wildlife Fund, Earth Force, and WQED/Pittsburgh 1997.
  • Meersman, Tom. “Conference Provides Update on Deformed Frog Research”. Star Tribune, 5 Dec. 1997.
  • ---. “The Observatory: The Appearance of Deformed Frogs”. Star Tribune, 25 March 1998.
  • Phillips, Kathryn. Tracking the Vanishing Frogs: An Ecological Mystery, St. Martin’s Press, 1994.


Activity adapted from Biodiversity Basics—An Educator’s Guide to Exploring the Web of Life, a resource of World Wildlife Fund’s Windows on the Wild biodiversity education program. For more information on WOW please visit www.worldwildlife.org/windows .

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