Unit 2: WhatAre Natural Hazards
and How Do Societies Respond
to Them?
Individuals and Societies - IB MYP
Year 2
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2.
How Is theEarth Structured?
Lesson Overview
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3.
Key Concept: Systems
•A system consists of interconnected parts that
work together as a whole. Earth's internal
structure and its dynamic processes—like
convection currents—form a system that
influences surface phenomena.
4.
Related Concept: Resources
•Resources are materials, energy, or features
that societies use. Earth's internal layers
provide vital resources—like geothermal
energy and minerals—shaping how societies
respond to natural hazards.
5.
Global Context: Time,Place and
Space
• This context helps us explore Earth's structure
across different timescales and places, linking
Earth's inner workings to the impact on our
planet over time.
6.
Unit of Inquiry
•Societies can be affected by different types of
hazards, and require innovative SYSTEMS and
RESOURCES in order to respond effectively to
them.
7.
Factual Questions
• •How is the Earth structured?
• • What are plate tectonics?
• • What are the causes and consequences of
earthquakes and volcanoes?
8.
Earth's Layers
• Earthhas four main layers:
• - Inner Core: Solid iron-nickel, extremely hot
(~5,700 °C)
• - Outer Core: Liquid iron-nickel, generates
Earth's magnetic field
• - Mantle: Solid but flowable silicate,
convection drives tectonics
• - Crust: Thin outer shell, oceanic and
continental types
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9.
Lithosphere & Asthenosphere
•- Lithosphere: Rigid outer shell including crust
and upper mantle, broken into plates
• - Asthenosphere: Semi-molten ductile layer
beneath lithosphere; plates glide over it
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10.
Convection Currents
• Heatfrom deep Earth causes mantle material
to rise when hot and sink when cooler.
• This creates convection currents that slowly
move tectonic plates.
Insert CONVECTION CURRENTS diagram here
11.
Plate Tectonics: Effectsof Mantle
Convection
• Convection currents cause plates to:
• - Spread apart (mid-ocean ridges)
• - Collide and sink (subduction zones)
• These lead to earthquakes, volcanoes, and
mountain building.
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12.
Lesson Summary
• •Earth is structured in layers—core, mantle,
crust
• • Mantle convection drives Earth's dynamic
system
• • Plate tectonics shape Earth's surface—
hazards like earthquakes and volcanoes
13.
Research Activity
• Workingin pairs or small groups:
• 1. Select one natural hazard (earthquake or
volcano)
• 2. Research how Earth's structure and
convection currents cause it
• 3. Create a simple diagram or concept map
• 4. Be ready to explain your findings in class
14.
Review Questions (Teacher-Led)
•• What are the four layers of the Earth?
• • How does the outer core contribute to
Earth's magnetic field?
• • What is the difference between lithosphere
and asthenosphere?
• • How do convection currents move tectonic
plates?
• • Name one hazard linked to plate tectonics
and why it occurs
