- Discuss and define the term "scientific theory."
- Watch segments fromDiscovery Science Library: The Basics: Earth Science.
- Work in small groups to draft an overview of one theory explored in the program, which includes details about the theory’s evidence and significance.
Discovery Science Library: The Basics: Earth Science
- Computer with Internet access
- Newsprint and markers
- Begin the lesson by asking students if they know what a "scientific theory" is. Write their ideas on a sheet of newsprint. Before continuing with the lesson, help students understand the following:
- A scientific theory is an idea that is grounded in scientific evidence and explains a wide range of observations.
- Over time, a scientific theory holds up. Many scientists working in different locations can corroborate the evidence for the theory.
- Scientists continue to find evidence to support a scientific theory.
- A scientific theory adds to our growing understanding of the world and how it works.
- Explain that students are going to watch the four segments inDiscovery Science Library: The Basics: Earth Sciencethat explore scientific theories ? Extinction, Earth's Magnetic Field, Blue Hole, and Plate Tectonics.
- After students have viewed the segments, divide them into small groups of three or four. Ask each group to select a theory. (Try to make sure that all four theories are covered.) Have the groups draft an overview of their theory that includes the following information:
- A brief summary of the theory
- Evidence for the theory
- The significance of the theory
- Give students time in class to work on their projects. Most of the information students need is in the segments, but they can visit the following Web sites for additional facts:
- During the next class, give students a few minutes to meet with their groups and finish the overviews. Then ask for volunteers to present group overviews. Make sure that each theory is covered in the presentations.
- Conclude the lesson by asking students: What did you learn about scientific theories that you didn't know before? Why are scientific theories important? What can they teach us about the world?
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Use the following three-point rubric to evaluate students' work during this lesson.
3 points: Students were highly engaged in class and small-group discussions; produced a clear and accurate overview describing a scientific theory, with all the requested components.
2 points: Students participated in class and small-group discussions; produced an adequate overview describing a scientific theory, with most of the requested components.
1 point: Students participated minimally in class and small-group discussions; produced an incomplete overview describing a scientific theory, with little or none of the requested components.
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Definition:A large, underwater cave in the Caribbean Sea, off Grand Bahama Island
Context:The presence of fossilized bat droppings and red dust, which probably blew in from the Sahara Desert when the cave was above sea level, are two pieces of evidence supporting the theory that this blue hole was once dry.
continental drift theory
dinosaur extinction theory
Definition:States that Earth was once a single giant landmass that separated and drifted apart over millions of years
Context:Alfred Wegener was the first scientist to propose the theory of continental drift, but it took more than 50 years before this idea was widely accepted.
Definition:States that a giant meteor struck Earth, changing the climate and bringing about the extinction of the dinosaurs
Context:Although not all scientists agree with the prevalent dinosaur extinction theory, it is clear that the extinction of the dinosaurs made it possible for mammals to dominate and diversify.
Earth's magnetic field
plate tectonics theory
Definition:The area between Earth's magnetic north and south poles; Earth's magnetic field is huge and extends into space.
Context:By studying lava flows, scientists have learned that the orientation of Earth's magnetic field changes; the last shift took place about 700,000 years ago.
Definition:States that Earth is divided into plates that are constantly moving
Context:The theory of plate tectonics states that earthquakes and volcanoes tend to occur in weak spots along the boundaries of plates.
Definition:An idea that is based on scientific evidence, can explain a wide range of observations, and holds up over time
Context:Many scientific theories, such a the theory of continental drift and the theory of plate tectonics, are important because they help explain what our planet once looked like and how it continues to change.
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Mid-continent Research for Education and Learning (McREL)
McREL’s Content Knowledge: A Compendium of Standards and Benchmarks for K–12 Education addresses 14 content areas. To view the standards and benchmarks, visitwww.mcrel.org/compendium/browse.asp.
This lesson plan addresses the following national standards:
National Academy of Sciences
- Science: Earth and Space Sciences ? Understands Earth's composition and structure
- Language Arts: Viewing ? Uses viewing skills and strategies to understand and interpret visual media
The National Academy of Sciences provides guidelines for teaching science in grades K–12 to promote scientific literacy. To view the standards, visitbooks.nap.edu/html/nses/html/overview.html#content.
This discussion guide addresses the following Grades 5-8 science standards:
- Earth and Space Science: Structure of the earth system; Earth's history
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