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Overview:
Have you ever watched a tadpole morph into a frog? National Geographic Emerging Explorer Tyrone Hayes says that, as a child, watching this animal—an animal that is really two animals—led him to his career in biology and herpetology. He didn't know it at the time, but watching tadpoles metamorphose into frogs may help us find causes of—and maybe even cures for—cancer. In this lesson, students will learn about the ways Hayes uses a combination of laboratory and field study to learn about frogs' developmental changes as they relate to chemical contamination of water. Students will investigate two areas where this research is sounding some alarms both for caution and for more research.
Connections to the Curriculum:
Geography, social studies, science
Connections to the National Geography Standards:
Standard 6: "How culture and experience influence people's perceptions of places and regions"
Standard 14: "How human actions modify the physical environment"
Standard 18: "How to apply geography to interpret the present and plan for the future"
Time:
Two to three hours
Materials Required:
- Computer with Internet access
- Writing paper and pens
Objectives:
- learn about the life and work of Tyrone Hayes;
- explain how Hayes's cultural and life experiences influenced his career choice and locations of study; and
- explain how studying animals' development may provide insight into environmental hazards—and cures—for humans.
Geographic Skills:
Acquiring Geographic Information
Organizing Geographic Information
Answering Geographic Questions
Analyzing Geographic Information
S u g g e s t e d P r o c e d u r e
Opening:
Ask students if they have ever heard frogs make noise late at night. Is it a sound they enjoyed or did it keep them awake? Have students listen to the collection of sounds available at Exploratorium's Frog Tracker ( Macromedia Shockwave required). Tell students that frog calls generally are a signal of mating, though many frogs call out all throughout the year. But some frogs have another way of calling out, or signaling, distress—and they don't even know they're doing it!
Development:
Explain to students that we never know where new ideas and information can come from, and that they may be surprised how much frogs can tell us about our own health and environment. Tell students they will be surprised to know how Tyrone Hayes's childhood interest in frogs spurred a career that may even be helping in the fight against cancer!
Activity 1:
Introduce students to Hayes by having them read a profile of his life and work.
Ask for students' reactions to the information they read about Hayes. How did Hayes become interested in studying frogs? Where has he done his fieldwork? How does he believe that studying frogs can help humans?
Have students visit the National Geographic magazine feature The Fragile World of Frogs and the Exploratorium online exhibit profiling Hayes and his studies to learn about how the world's frog populations are affected by the environment, and the ways in which those frog populations can be seen as alarm systems for human health.
Students should use the available resources to answer these questions in writing, or by creating a small group oral report:
- What similarities are there between frogs and humans?
- What are some reasons that frogs make good research subjects?
- Where has Hayes done field research? Why does he spend so much time in the field? Why not just work in a lab?
- Why are frogs good subjects to use when studying the potential effects of contaminants?
- What are the potential long-term benefits of Professor Hayes's research?
Activity 2:
Have students select one of two primary areas in which frog studies are helping to provide information—pesticide use and cancer—and conduct research using the provided resources to learn about how frog studies are advancing science in these areas. Students should use the information they learn to prepare a flyer or brochure in support of an action they feel should be taken in relation to their topic (e.g., promote or decry a ban on atrazine; advocate for more specific research on potential cancer cures; or, arguing against the use of frogs for research).
Atrazine
- What is atrazine? What are its uses?
- How does atrazine get into the water supply?
- What impact have researchers noticed on frogs exposed to atrazine present in the water supply?
- What are the implications for human health?
- What kinds of problems would a ban on atrazine cause?
National Geographic News: Pesticides, Parasite May Cause Frog Deformities
National Geographic News: Hermaphrodite Frogs Caused By Popular Weed Killer?
Amphibian Conservation Alliance: FROGS.org—You Decide: Atrazine Ban
Wreaking Havoc with Life: Minute atrazine levels lead to hermaphroditic frogs, cancer (PDF, Adobe Acrobat Reader required)
Earth Day Network: Water for Life—Pesticides
Cancer
- Why are frogs "ideal candidates" for research studies? What are the negative arguments about using them?
- What are some of the risks humans face from synthetic hormones in the environment?
- How are African reed frogs particularly well-suited for studies on estrogen?
- What research has Hayes done regarding "safe" levels or doses of potential carcinogens (cancer-causing agents)?
- What are the positive aspects of Hayes's work with cancer agents and blockers?
Exploratorium: Advantages of Frogs (audio file, RealPlayer required)
Exploratorium: Frogs—Environmental Sentinels
Earth Day Network: Toxics and Water
Exploratorium: The Cancer Connection
Have students use this interactive Print Press to create flyers or brochures they can send to a state or national official requesting attention be paid to their opinion on the issue they have researched.
Closing:
Ask students to reflect on the ethics of using frog populations as detection devices for environmental contaminants. What are the implications, both positive and negative, for science and health? Suggest that students consider the consequences of raising frog populations specifically for this purpose (amphibian population would increase, thwarting the current decline, but the exposure of these new populations to the various scientific research tests could be detrimental to frogs in general).
Suggested Student Assessment:
Student flyers should reflect a clear understanding of the information they have studied. While there are clearly varied opinions on these issues, students should demonstrate their awareness of the importance of the studies.
Extending the Lesson:
- Have students visit National Geographic Explorer magazine's Freaky Frogs to learn more about extinct and declining populations of frogs, the causes of those declines, and what can be done to improve frogs' condition in the world. Students may also wish to visit these sites for more information:
NBII: FrogWeb—Amphibian Declines
Australia National Parks & Wildlife Service: Threats to Frogs
Vanishing Frogs
- Suggest that students learn more about water conservation and health issues by visiting the Earth Day Network's Water for Life action pages. What's in Your Water has a comprehensive guide to water quality, with suggestions for citizen action on a local and global scale.
- Have students learn more about frogs and their natural v. unnatural habitats in these two articles about "leaping" frogs, frogs that have moved from their natural locations to new areas. Have students find out what problems can be caused for the areas where these frogs have landed.
National Geographic News: Invading Bullfrogs Appear Nearly Unstoppable
Amphibian Conservation Alliance: FROGS.org—Stowaway Frogs Raise Fears
- Have students read about National Geographic's Strange Days on Planet Earth, a four-part PBS series in which both Tyrone Hayes and Tierney Thys, two of National Geographic's Emerging Explorers, participate. The series uses storytelling to explore new discoveries about the health of the planet. Have students visit Sea Studios' online summary of the series, in particular "Episode Four: Troubled Waters," to learn about the interaction between marine life and one of the industries presented (farming, agriculture, fishing). Ask students to conduct further research into one of the issues discussed—bycatch or waterway contamination—and present a brief summary.
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