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Grades 3-5
Overview:
Frogs are amazing creatures. National Geographic Emerging Explorer Tyrone Hayes points out that they're really two animals—they have all the mechanisms to be both a tadpole and a frog. His fascination with frogs and their development led him to his current career in biology and herpetology—and a long way to finding 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 the controversial issues surrounding the use of a chemical called atrazine and calls for its ban.
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:
Students will
  • 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;
  • explain how studying animals' development may provide insight into environmental hazards; and
  • examine the issues around the uses and potential hazards of the chemical atrazine.
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 has uncovered a potential problem with one of the most commonly used chemicals in the world.

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:

  1. What similarities are there between frogs and humans?
  2. What are some reasons that frogs make good research subjects?
  3. Where has Hayes done field research? Why does he spend so much time in the field? Why not just work in a lab?
  4. Why are frogs good subjects to use when studying the potential effects of contaminants?
  5. What are the potential long-term benefits of Professor Hayes's research?
Activity 2:
Have students do some research into one of Dr. Hayes's primary interests—pesticide use and the implications for human health. Students should use the provided resources to learn about how frog studies helped to draw attention to the important issue of atrazine use. Students should use the information they learn to create a presentation on this important topic.

Atrazine

  1. What is atrazine? What are its uses?
  2. How does atrazine get into the water supply?
  3. What impact have researchers noticed on frogs exposed to atrazine present in the water supply?
  4. What are the implications for human health?
  5. 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

Have students create posters and short speeches to draw attention to this issue. Students do not need to take a position, and in fact should prepare presentations that articulate both sides of the issue. The goal of the presentations should be to draw attention to the fact that the issue exists, and get people to pay attention and learn more.

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 presentations should reflect a clear understanding of the information they have studied. While there are clearly varied opinions on the issue of atrazine use, students should demonstrate their awareness of the importance of the studies.
Extending the Lesson:
Related Links: