Spheres of the Earth

Grade 7 · General Science

Semester 2 | Period 5 | Week 28

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Subject: General Science

Semester: 2

Period: 5

Week: 28

School Name:
Teacher’s Name:
Subject: General Science
Grade Level: Grade 7
Date:
Week 28 Lesson Duration: 45 minutes
Week & Period: Week 28, Period 5
Topic: Spheres of the Earth
Sub-topic: Hydrosphere, Lithosphere, Mantle and Core
Learning Objectives
By the end of the lesson, students should be able to:

  1. Define and describe the different spheres of the Earth.
  2. Explain the importance of the hydrosphere and lithosphere to life.
  3. Identify and describe the mantle and core of the Earth.

Previous Knowledge
Students already know:
• That the Earth is round and made up of land and water.
• That people live on land and depend on water for survival.
Instructional Materials
• Textbook: General Science textbook for Grade 7
• Teaching aids: Globe or world map, chart showing Earth’s structure (layers), model of Earth’s cross-section, chalk/marker and board
• Students’ notebooks and writing materials
Lesson Development – ABC Model
A – Anticipation (Warm-up / Starter)
Time: 5–10 minutes
Activity: The teacher will ask the class:
• What covers most of the Earth’s surface, land or water?
• Where do plants, animals, and humans live?
• Do you think the Earth is solid all through or does it have layers?
The teacher will record their responses on the board.
Teacher’s Role: Encourage brainstorming, correct misconceptions, and guide students toward the concept of Earth’s spheres.
Learner’s Role:
• Share their prior knowledge about Earth.
• Participate actively by giving responses.

B – Building Knowledge (Main Lesson Body)

Time: 25–30 minutes

Teacher’s Role (Expanded & Detailed):

  1. Introduce the concept of Earth’s “spheres.”
    • Begin by explaining that Earth is made up of different parts (or spheres) that work together to support life.
    • Use a globe, diagram, or chart to show the Hydrosphere, Lithosphere, Mantle, and Core.
  2. Hydrosphere (Water part of Earth):
    • Define the hydrosphere as all the water on Earth, covering about 70% of the planet’s surface.
    • Examples: oceans, seas, rivers, lakes, ponds, glaciers, groundwater, rainfall.
    • Emphasize its importance: provides drinking water, supports farming, allows fishing, and regulates temperature.
    • Local link: Liberia is bordered by the Atlantic Ocean, which affects rainfall and weather. Rivers like St. Paul and Cavalla provide water, fish, and transport.
  3. Lithosphere (Land part of Earth):
    • Define lithosphere as the solid outer layer of the Earth made up of rocks, soil, and landforms.
    • Examples: mountains, valleys, plains, plateaus.
    • Importance: provides land for houses, farming, roads, and minerals.
    • Local link: Liberia’s lithosphere is rich in resources such as iron ore, gold, diamonds, and fertile soil for agriculture.
  4. Mantle (Middle layer inside Earth):
    • Define mantle as the thick layer beneath the lithosphere.
    • Made of hot, semi-molten rocks (magma).
    • Movement of mantle rocks causes volcanic eruptions and
    • Helps recycle Earth’s crust through volcanic activity.
  5. Core (Center of Earth):
    • Introduce the core as the innermost part of the Earth, divided into:
      • Outer core: Made of liquid iron and nickel. Responsible for Earth’s magnetic field, which protects the planet from harmful solar radiation.
      • Inner core: Solid, very hot, also made of iron and nickel. It is the densest part of Earth.
    • Explain how the core’s heat drives mantle movement, which in turn influences volcanic activity and mountain building.
  6. Connect the lesson to daily life in Liberia/Africa:
    • Hydrosphere: oceans bring rain and support fishing.
    • Lithosphere: rich mineral deposits (iron ore, diamonds, gold) help the economy.
    • Mantle & Core: though unseen, they shape land through volcanoes, earthquakes (in other parts of Africa, e.g., East Africa Rift Valley).

 

Learners’ Activities (Expanded):

  • Observation: Examine the globe, maps, and teacher’s charts showing Earth’s layers.
  • Drawing Exercise: Each learner draws and labels a simple cross-section diagram of the Earth, showing Crust/Lithosphere → Mantle → Outer Core → Inner Core.
  • Classification Activity: In groups, students classify given items or examples into:
    • Hydrosphere: river, rain, ocean.
    • Lithosphere: mountains, soil, diamond, farmland.
    • Mantle/Core: magma, molten metals, earthquakes.
  • Discussion: Groups discuss and present why the hydrosphere and lithosphere are very important to human survival.

 

Assessment Checks (Expanded):

  • Teacher asks oral questions such as:
  1. What is the hydrosphere? Give two examples.
  2. What is the lithosphere? Mention two things found in it.
  3. What lies beneath the lithosphere?
  4. What is the difference between the outer core and inner core?
  5. Why is the hydrosphere important for life in Liberia?
  • Learners label a teacher-drawn blank diagram of Earth’s layers.
  • Quick quiz game: Teacher names an item (e.g., “Rain,” “Diamond,” “Magma”), students shout out whether it belongs to Hydrosphere, Lithosphere, or Mantle/Core.

 

Notes (Expanded & Detailed):

  • Hydrosphere: All water on Earth—oceans, seas, lakes, rivers, rain, ice, and groundwater. Covers 70% of the Earth’s surface. Important for drinking, farming, fishing, transportation, and climate regulation.
  • Lithosphere: The solid outer part of Earth made of rocks, soil, and landforms. Provides land for human settlement, farming, and minerals for development.
  • Mantle: The thick middle layer beneath the crust, made of hot semi-molten rock (magma). Its movement causes volcanoes and earthquakes.
  • Core: The deepest part of Earth.
    • Outer Core: liquid iron and nickel, produces Earth’s magnetic field.
    • Inner Core: solid iron and nickel, very hot and dense.
  • Together, these parts make Earth habitable by supplying resources, regulating climate, and shaping landforms.

 

C – Consolidation (Conclusion & Assessment)
Time: 5–10 minutes
Summary:
• The teacher will ask students to recall:

  • Define hydrosphere and lithosphere.
  • Name two examples of the hydrosphere.
  • State the difference between the mantle and the core.
    Evaluation Method (Expanded):
    • Exit slip/quiz: Students will write short answers to:
  1. Define hydrosphere.
  2. Define lithosphere.
  3. State two differences between the mantle and the core.
    Teacher will collect and review answers for understanding.
    Assignment (Expanded):
    • Draw a well-labeled diagram of the Earth showing lithosphere, mantle, and core.
    • Write three ways in which water (hydrosphere) is important to life.
    Differentiation / Inclusive Strategies
    • Struggling Learners: Use simplified diagrams and real-life examples (e.g., rivers, mountains).
    • Advanced Learners: Research how earthquakes and volcanoes are related to the mantle.
    • Students with Disabilities: Provide large-print diagrams and allow oral descriptions instead of written tasks.
    Teacher’s Reflection (After Class)
    • What worked well? ______________________________________________________
    • What needs improvement? _________________________________________________
    • Students’ engagement level: □ High □ Medium □ Low