PRIMARY 4: AGRIC SCIENCES – FIRST TERM | WEEK 4

TOPIC: FORMATION OF SOIL

A: TEACHING AND LEARNING MATERIALS

1. Pieces of rocks.
2. Soil samples.
3. Pictures showing weathered rocks.
4. Water.
5. Charts showing agents of soil formation.

B: REFERENCE MATERIALS

1. Scheme of work.
2. Recommended Agric Sciences textbook for Primary 4.
3. Online educational resources.

C: PREVIOUS KNOWLEDGE

The pupils have learnt the meaning and types of soil and can describe some of their characteristics.

D: PERFORMANCE OBJECTIVES

By the end of the lesson, pupils should be able to:

1. Explain soil formation.
2. Explain weathering.
3. Name agents of soil formation.
4. Describe how water and wind help to form soil.
5. Explain how plants and animals help in soil formation.

E: CONTENT

Meaning of Soil Formation

Soil formation is the process by which rocks break down into small particles that later form soil.

Meaning of Weathering

Weathering is the breaking down of rocks into smaller pieces. It takes place slowly over many years.

Agents of Soil Formation

Agents of soil formation include:

1. Water
2. Wind
3. Changes in temperature
4. Plants
5. Animals

Water

Rainwater enters cracks in rocks. With time, the cracks become bigger and pieces of rock break off. 💧 + 🪨 → smaller rock particles

Wind

Strong wind carries sand and small stones. These rub against rocks and gradually wear them away.

Changes in Temperature

Rocks become hot during the day and cool at night. Continuous heating and cooling can cause rocks to crack.

Plants

Plant roots grow into cracks in rocks. As the roots become bigger, they can break the rocks apart. 🌱 Roots can help break rocks.

Animals

Animals such as earthworms, ants and rodents dig into the ground. Their activities help to mix and loosen the soil.

F: LESSON PRESENTATION

F1: Teachers’ Activities

1. Shows pupils pieces of rocks and soil.
2. Explains soil formation.
3. Explains weathering.
4. Discusses agents of soil formation.
5. Demonstrates how water enters cracks.
6. Explains the effects of plant roots and animals.

F2: Pupils’ Activities

1. Observe rocks and soil.
2. Explain soil formation.
3. Define weathering.
4. Name agents of soil formation.
5. Describe how plants and animals help to form soil.

G: CONCLUSION

The teacher revises weathering and the different agents responsible for soil formation. The teacher encourages pupils to observe broken rocks, plant roots and soil around their environment.

H: EVALUATION GUIDE

Pupils should be able to answer the following questions:

1. What is soil formation?
2. What is weathering?
3. Name four agents of soil formation.
4. How does water help to break rocks?
5. How do plant roots help in soil formation?
6. Name one animal that helps to mix the soil.