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Online Lessons for Teachers: Learning Evolution


What Is the Nature of Science?

View LESSON 1 Student Page

Activity 1: A Survey about Science

Activity 1: Teacher Notes

Activity 2: What Killed the Dinosaurs?

Activity 3: Ancient Farmers of the Amazon

Activity 3: Teacher Notes

Materials You'll Need:
•  Hypotheses Support form
•  Best Explanation form

Activity 2 Teacher Notes: What Killed the Dinosaurs?

When several explanations are proposed for a phenomenon, how do scientists decide which one is right? In this activity, students learn about the current hypotheses for dinosaur extinction, select the one that seems most reasonable, and gather information to both support and refute it. Students will learn that there is not always a known right answer in science. Sometimes there are questions that have not been answered and may never be answered.

Learning Goals


To provide a foundation for understanding how scientists use evidence to formulate hypotheses


To have students understand that there may be more than one hypothesis formed to explain a single phenomenon


To have students understand that evidence can be used to support more than one hypothesis


To help students understand that science is not a set of revealed truths (based on faith and the supernatural), but is based on discoveries and evidence found in nature

Part A: Reconstructing the Past


Review with your students the definition of a scientific hypothesis.


Students will visit the University of California Berkeley Museum of Paleontology site and collect information on the Cretaceous and Paleocene time periods. They will write a page describing this time period from the point of view of someone on Earth at that time. If they need assistance, you might ask: What kinds of plants do you see? What kinds of animals? Describe the arrangement of the continents. What does the environment look like?

Part B: Several Possible Explanations


Next, have students visit the What Killed the Dinosaurs? Web activity and read hypotheses for dinosaur extinction. They will take notes on the hypotheses and the evidence that support them. Then they will select the hypothesis they find most reasonable.

 Screen grab from the What Killed the Dinosaurs? Web activity.

What Killed the Dinosaurs?


Divide the class into groups of four to five students. Have students discuss the hypotheses they chose and the evidence for and against them. Ask them to print the Hypotheses Support form and Best Explanation form or distribute them yourself.


After groups have had enough time to share hypotheses and answer the discussion questions, have a quick follow-up discussion with the entire class. Discuss how scientists form hypotheses, why some hypotheses carry greater weight than others, and whether we will ever be able to solve the mystery of dinosaur extinction. Reinforce the idea that science is a process of establishing cause and effect, not merely finding answers in books or on Web sites. Ask students to think about ways they could "test" their hypotheses.

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