National Geographic News Teacher Sheet

National Geographic News Teacher Sheet


In this exercise, students will learn about scientific debates, alternative hypotheses, and how there can be more than one explanation for the same set of scientific evidence by reading the National Geographic News online article “Hermaphrodite Frogs Caused by Popular Weed Killer?”

After reading the article, students should answer these questions:

Using your own words, state Tyrone Hayes’ explanation, in the form of a scientific hypothesis, for the cause of abnormal sexual development in male frogs.
Answers will vary. Encourage students to explain their answers.

Provide an example of evidence cited by Tyrone Hayes to explain his theory for abnormal sexual development observed in male frogs. 
Tadpoles exposed to 0.1 ppb atrazine had abnormal reproductive systems.

Provide an example of scientific evidence cited by Ernest Smith and John Giesy explaining why they disagree with Tyrone Hayes’ theory.
They did not detect abnormalities in frogs exposed to atrazine at concentrations below 25 ppb.

Do you think that Dr. Hayes’ suspicion that increasing levels of the enzyme aromatase (which converts testosterone to estrogen) in male frogs is explanation or evidence for their feminization? Explain your answer.
Evidence; according to the article, “Hayes’ team suspects that atrazine feminizes the frogs by increasing the production of an enzyme called aromatase.” Since there is no data to support this theory, it is a possible explanation.

What are some possible explanations for the difference in opinion between Hayes and Smith and Giesy? 
 Differences in experimental design and conditions, differences in the tools and methods used for gathering and analyzing data, centering on evidence that confirms their current beliefs and concepts (i.e., personal explanations), ignoring or failing to perceive evidence that does not agree with their ideas, designing studies to achieve a desired outcome. (Refer to the misconceptions listed in the Context section of this lesson.)

Based upon what you read, use your own words to define peer review.
Answers will vary. Encourage students to explain their answers.

Why is peer review important in science?
Scientific findings need to be critically reviewed for the work to be validated, to identify errors, to consider alternate explanations, to determine if more work is needed, or if the studies need to be repeated.

This teacher sheet is a part of the The Frog Scientist 2: Schoolyard Field Investigation lesson.

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