Liberia - Grade 7 - General Science

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Subject: General Science

Semester: 2

Period: 5

Week: 29

School Name:
Teacher’s Name:
Subject: General Science
Grade Level: Grade 7
Date:
Week 29 Lesson Duration: 45 minutes
Week & Period: Week 29, Period 4
Topic: Crust of the Earth
Sub-topic: Rock Formation, Types of Rocks, Rock Cycle, and Mineral Resources in Liberia

Learning Objectives
By the end of the lesson, students should be able to:

Define and explain how rocks are formed.
Identify and describe the three main types of rocks: igneous, sedimentary, and metamorphic.
Explain the rock cycle with examples.
Mention some important mineral resources from rocks found in Liberia.

Previous Knowledge
Students already know:
• That the Earth has a crust, mantle, and core.
• That land is made of soil, stones, and rocks.

Instructional Materials
• Textbook: General Science textbook for Grade 7
• Teaching aids: Chart of rock cycle, rock samples (if available), diagram of Earth’s crust
• 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 do you think the land we walk on is made of?
• Have you seen stones or big rocks before? Where?
• Do you think rocks are useful to people?
The teacher will record their responses on the board.

Teacher’s Role: Guide students to connect their knowledge of land/soil to the concept of rocks.
Learner’s Role:
• Share prior experiences with rocks and minerals.
• Respond actively during discussion.

B – Building Knowledge (Main Lesson Body)

Time: 25–30 minutes

Teacher’s Role (Expanded & Detailed):

Introduce the Crust of the Earth:
- Explain that the crust is the solid outer layer of the Earth, like the “skin” of the planet.
- It is very thin compared to the mantle and core, but it is where all human, animal, and plant life exists.
- The crust is made up of different types of rocks which contain minerals.
Explain Rock Formation (Natural Processes):
- Rocks are not man-made; they are formed through natural processes over millions of years.
- Key processes include:
  - Cooling of magma or lava → leads to igneous rocks.
  - Deposition and compression of sediments → leads to sedimentary rocks.
  - Heat and pressure deep underground → changes rocks into metamorphic rocks.

Introduce the Three Main Types of Rocks (with examples):
- Igneous Rocks:
  - Formed when hot molten rock (magma or lava) cools and becomes solid.
  - Examples: Granite (used in construction) and Basalt (forms after volcanic eruptions).
  - Importance: Often strong and durable; source of some minerals.
- Sedimentary Rocks:
  - Formed when sand, clay, shells, or plant/animal remains build up in layers and get compressed over time.
  - Examples: Limestone (used to make cement), Sandstone.
  - Importance: They often contain fossils and are a source of natural resources like oil, gas, and coal (though not common in Liberia).
- Metamorphic Rocks:
  - Formed when existing igneous or sedimentary rocks are changed by heat and pressure deep underground.
  - Examples: Marble (used for decoration and building), Slate (used for roofing).
  - Importance: Many are valuable for construction and industry.

Explain the Rock Cycle:
- Show that rocks are not fixed — they keep changing from one type to another in a continuous cycle.
- For example:
  - Igneous rock can break down into sediments → form sedimentary rock.
  - Sedimentary rock can be changed by heat/pressure → become metamorphic rock.
  - Metamorphic rock can melt → form magma → cool again into igneous rock.
- Stress that the rock cycle recycles Earth’s materials and makes new resources available.

(Cooling & Solidification)

Magma ----------------------> Igneous Rock

^ |

| | (Weathering & Erosion)

| v

(Melting) <---------------------- Sediments <--- (Breakdown of rocks)

| |

| v

| Sedimentary Rock

| |

| (Heat & Pressure) |

| v

<---------------------- Metamorphic Rock

Explanation (to go with the sketch):

Magma cools → forms Igneous Rocks.
Igneous Rocks break down into sediments → compressed into Sedimentary Rocks.
Sedimentary Rocks change under heat & pressure → become Metamorphic Rocks.
Metamorphic Rocks can melt again → form Magma → cycle continues.

Connect to Liberia and Africa (Local Relevance):
- Liberia’s crust is rich in minerals such as:
  - Iron ore – used in steel production.
  - Gold and diamonds – valuable export minerals.
  - Bauxite – used for making aluminum.
- These minerals are products of the rock cycle and form the foundation of Liberia’s economy.
- Other African countries like South Africa (gold/diamonds) and Guinea (bauxite) also depend on rock-based resources.

Learners’ Activities (Expanded):

Observation:
- Study teacher’s charts/diagrams showing the three rock types and the rock cycle.
- Observe real rock samples if available (granite, limestone, marble).
Classification Activity:
- In groups, classify rock samples (real or drawn pictures) into igneous, sedimentary, and metamorphic.
Group Discussion:
- Discuss how minerals found in Liberia (iron ore, gold, diamond, bauxite) help the economy through jobs, trade, and development.
Drawing & Labeling:
- Each learner draws a simple diagram of the rock cycle showing arrows connecting igneous → sedimentary → metamorphic → back to igneous.
Mini-Presentation:
- Groups present one type of rock, how it is formed, examples, and uses in Liberia.

Assessment Checks (Expanded):

Teacher asks:

What are the three main types of rocks?
How are igneous rocks formed? Give an example.
Which type of rock may contain fossils?
How are metamorphic rocks formed? Give an example.
Mention one mineral found in Liberia and its use.

Short activity: Teacher names a rock (e.g., marble, sandstone, granite), learners quickly state its type.

Notes (Expanded & Detailed):

The Earth’s crust is the outermost layer made of rocks.
Rocks are naturally formed solid materials made up of minerals.
Types of rocks:

Igneous Rocks – formed by cooling of magma or lava (e.g., granite, basalt).
Sedimentary Rocks – formed by deposition and compression of sediments (e.g., limestone, sandstone).
Metamorphic Rocks – formed when rocks change under heat and pressure (e.g., marble, slate).

Rock Cycle: Shows that rocks can change from one type to another through melting, cooling, weathering, compression, heat, and pressure.
Liberia’s Rocks & Minerals:

Iron ore – used in making steel.
Gold & diamond – used for jewelry and as export resources.
Bauxite – used in aluminum production.

Rocks are essential for construction, industry, economy, and human survival.

C – Consolidation (Conclusion & Assessment)
Time: 5–10 minutes

Summary:
• The teacher will ask students to recall:

Define the crust of the Earth.
Mention the three types of rocks.
Explain one way the rock cycle works.
List two mineral resources found in Liberia.

Evaluation Method (Expanded):
• Exit slip/quiz: Students will write short answers to:

Define the rock cycle.
State two examples of sedimentary rocks.
Mention two mineral resources found in Liberia.
Teacher will review and provide quick feedback.

Assignment (Expanded):
• Draw and label the rock cycle in your notebook.
• Write a short paragraph on the importance of one mineral resource (e.g., iron ore, diamond) to Liberia’s economy.

Differentiation / Inclusive Strategies
• Struggling Learners: Use simplified diagrams and provide real-life examples of rocks.
• Advanced Learners: Research how rocks are used in construction, jewelry, and industry.
• Students with Disabilities: Provide large-print diagrams and allow oral responses.

Teacher’s Reflection (After Class)
• What worked well? ______________________________________________________
• What needs improvement? _________________________________________________
• Students’ engagement level: □ High □ Medium □ Low