Students Will Be Able To (SWBAT): Classify the layers of the Earth—crust, mantle, outer core, and inner core—based on density, thickness, temperature, and composition in order to formulate and ask questions for comparative analysis.
Key Concepts to Cover:
- Layers of the Earth:
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Crust:
- Thickness: 5-70 km
- Density: Low (approximately 2.7 g/cm³ for continental crust and 3.0 g/cm³ for oceanic crust)
- Temperature: Varies, generally increases with depth; averages about 20°C at the surface but increases with depth.
- Composition: Primarily silicate rocks (granite in continental crust, basalt in oceanic crust).
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Mantle:
- Thickness: About 2,900 km
- Density: Intermediate (about 3.3-5.7 g/cm³)
- Temperature: Ranges from about 500°C near the crust to around 4,000°C near the outer core.
- Composition: Mostly silicate minerals rich in magnesium and iron.
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Outer Core:
- Thickness: About 2,200 km
- Density: High (about 9.9-12.2 g/cm³)
- Temperature: Ranges from about 4,000°C to 6,000°C.
- Composition: Liquid iron and nickel, with lighter elements such as sulfur and oxygen.
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Inner Core:
- Thickness: About 1,200 km
- Density: Very high (about 12.8-13.1 g/cm³)
- Temperature: Estimated to be as hot as 5,000°C to 7,000°C.
- Composition: Solid iron and nickel.
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Comparative Questions:
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Density:
- How does the density of the crust compare to that of the mantle and outer core?
- Why does the outer core have a higher density than the mantle?
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Thickness:
- Which layer of the Earth is the thickest, and how does its thickness compare to that of the other layers?
- Why is the crust, despite being the outermost layer, the thinnest compared to the mantle and cores?
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Temperature:
- How do temperatures differ between the crust and the inner core?
- What factors contribute to the extreme temperatures found in the outer and inner cores compared to the crust and mantle?
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Composition:
- What are the main differences in composition between the continental crust and the oceanic crust?
- How does the composition of the outer core differ from that of the inner core?
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Understanding Layer Functions:
- How do the properties of each layer (density, thickness, temperature, composition) affect tectonic activity?
- Why is the inner core solid while the outer core is liquid, and how does this relate to Earth's geography and magnetic field?
Activity Suggestion:
After discussing these concepts and questions, students can create a visual representation (like a diagram) of the Earth’s layers, labeling their thickness, density, temperature, and composition. Students can also engage in group discussions to come up with additional comparative questions or conduct small experiments or demonstrations to explore geological concepts further.
Evaluation:
Assess students’ understanding through their participation in discussions, the accuracy of their diagrams, and the quality of their comparative questions. Consider a quiz at the end of the lesson focusing on the key concepts.