Class: Senior Secondary School 1 (SS1, SS 1, SSS1, SSS 1)
Term: 3rd Term
Week: 1
Age: 15 years
Duration: 45 minutes
Subject: Chemistry
Curriculum Theme: Chemistry
Previous Lesson: Hydrocarbons: Carbon Valency, Homologous Series and Saturated Hydrocarbons.
Topic: WATER
Subject Matter: sources of water, types of water: soft and hard water, water pollutants and uses of water, laboratory preparation of water and causes of hardness

Specific Objectives

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

Cognitive Domain:

Identify at least three properties of water.
List four common sources of water.
Define soft water and hard water.
Explain the causes of temporary and permanent water hardness.
Enumerate three water pollutants.
State four uses of water.
Describe the laboratory preparation of water.

Affective Domain:

Appreciate the importance of clean water for human health.
Suggest safe practices for water purification and conservation.

Psychomotor Domain:

Test water samples for hardness using soap.
Compare different water samples based on their lathering ability.

Discuss with peers the importance of clean water and methods to prevent water pollution in their communities.

Reference Materials

The following resources were used in planning this lesson:

9 Years Basic Education Curriculum (Senior Secondary School Chemistry)
State Unified Scheme of Work
New School Chemistry for Senior Secondary Schools by Osei Yaw Ababio

Instructional Materials

The teacher will teach this lesson with the aid of:

Charts illustrating the laboratory preparation and uses of water.
Water samples (e.g., river water, well water, tap water).
A bar of soap or liquid soap.
Samples of contaminated water (optional, for discussion).
Samples of hard water (e.g., bore-hole water).

Rationale for the Lesson

This lesson helps pupils understand the nature and importance of water, a fundamental substance in daily life and chemistry. It enables them to distinguish between different types of water and recognize the factors affecting water quality, which is important for health and environmental awareness.

Prerequisite/Previous Knowledge

Pupils have basic knowledge of water from their Junior Secondary School Integrated Science lessons, including its general uses and importance.

Lesson Content/Board Summary

WATER

Properties of Water

Water is a clear, colourless, odourless, and tasteless liquid. It boils at 100°C and freezes at 0°C. Water is a good solvent for many substances, earning it the name “universal solvent.” It is neutral to litmus paper.

Sources of Water

The following are common sources of water:

Rain water
Well water
River water
Spring water
Borehole water
Tap water

Types of Water: Soft and Hard Water

Water can be classified into soft and hard water based on its ability to form lather with soap.

Soft Water: This is water that readily forms lather with soap. It contains very few dissolved mineral salts.
Hard Water: This is water that does not readily form lather with soap. It contains dissolved mineral salts, mainly compounds of calcium and magnesium.

Causes of Water Hardness

Water hardness is caused by the presence of dissolved mineral salts, specifically ions of calcium (Ca²⁺) and magnesium (Mg²⁺).

Temporary Hardness: Caused by dissolved bicarbonates of calcium and magnesium (Ca(HCO₃)₂ and Mg(HCO₃)₂). This type of hardness can be removed by boiling.
Permanent Hardness: Caused by dissolved sulphates and chlorides of calcium and magnesium (e.g., CaSO₄, MgSO₄, CaCl₂, MgCl₂). This type of hardness cannot be removed by simple boiling.

Water Pollutants

Water pollutants are substances that contaminate water, making it unsuitable or unsafe for use. The following are examples of water pollutants:

Domestic waste (e.g., detergents, food scraps)
Industrial effluents (e.g., chemical waste, heavy metals)
Agricultural run-off (e.g., pesticides, fertilizers)
Sewage and human waste
Oil spills from vessels or pipelines
Pathogenic microorganisms (e.g., bacteria, viruses)

Uses of Water

Water has numerous uses in daily life and industries. The following are some uses:

Drinking and cooking
Washing and bathing
Industrial processes (e.g., as a solvent, coolant)
Agriculture (e.g., irrigation)
Generation of hydroelectric power
Transportation

Laboratory Preparation of Water

Water can be prepared in the laboratory by the combustion of hydrogen gas in the presence of oxygen or air. The reaction is:

2H₂(g) + O₂(g) → 2H₂O(l)

The water produced can be tested using anhydrous copper(II) sulphate, which turns from white to blue, or anhydrous cobalt(II) chloride paper, which changes from blue to pink, confirming the presence of water.

Teaching Methods/Instructional Techniques

Discussion, Lecture, Demonstration, Question and Answer, Visual Aids

Instructional Procedures

Step 1: Introduction

Time: 5 minutes
Teaching Skill: Set Induction
Teacher’s Activity: The teacher greets the pupils and asks them to mention some common liquids they use daily. The teacher then guides the discussion towards water, its importance, and asks pupils where they get water from in their homes and communities.
Pupils’ Activity: Pupils respond to the teacher’s questions, mentioning liquids like water, soft drinks, etc., and identify various sources of water.
Learning Point: Pupils recall prior knowledge about water and its importance.

Step 2: Properties and Sources of Water

Time: 10 minutes
Teaching Skill: Explanation/Observation
Teacher’s Activity: The teacher presents a clean sample of water and guides pupils to observe and state its properties (colour, odour, taste). The teacher then asks pupils to list various sources of water they know and writes them on the board.
Pupils’ Activity: Pupils observe the water sample and state its properties. They also contribute to listing different sources of water.
Learning Point: Pupils identify the physical properties of water and enumerate its sources.

Step 3: Types of Water: Soft and Hard Water

Time: 10 minutes
Teaching Skill: Demonstration/Explanation
Teacher’s Activity: The teacher demonstrates the difference between soft and hard water using samples (e.g., tap water and borehole water) and soap. The teacher adds soap to each sample and shakes, showing which one lathers easily. The teacher then defines soft and hard water and explains the causes of temporary and permanent hardness.
Pupils’ Activity: Pupils observe the demonstration and note the difference in lather formation. They listen to the definitions and explanations.
Learning Point: Pupils understand the concepts of soft and hard water and their causes.

Step 4: Water Pollutants and Uses of Water

Time: 5 minutes
Teaching Skill: Discussion/Brainstorming
Teacher’s Activity: The teacher asks pupils to brainstorm substances that can make water dirty or unsafe (pollutants) and discusses common uses of water in homes, industries, and agriculture. The teacher lists these points on the board.
Pupils’ Activity: Pupils mention various pollutants and uses of water.
Learning Point: Pupils identify common water pollutants and state the uses of water.

Step 5: Laboratory Preparation of Water

Time: 5 minutes
Teaching Skill: Explanation/Diagram
Teacher’s Activity: The teacher explains how water can be prepared in the laboratory by burning hydrogen gas in oxygen, writing the chemical equation on the board. The teacher also mentions the tests for water (anhydrous copper(II) sulphate and cobalt(II) chloride paper).
Pupils’ Activity: Pupils listen, copy the equation, and note the tests for water.
Learning Point: Pupils learn how water is prepared in the laboratory and how to test for it.

Step 6: Evaluation/Review

Time: 5 minutes

Teaching Skill: Questioning/Assessment

Teacher’s Activity: The teacher evaluates the learning by asking the following questions:

Define soft water and hard water.
List three sources of water.
State two causes of water hardness.
Mention three uses of water.
Enumerate two common water pollutants.

Pupils’ Activity: Pupils answer orally and in writing.

Learning Point: Pupils demonstrate understanding of the lesson.

Step 7: Conclusion

Time: 5 minutes
Teaching Skill: Summarization
Teacher’s Activity: The teacher summarizes the key points of the lesson, reiterating the importance of water, its types, sources, pollutants, and uses. The teacher also gives a take-home assignment: “Research methods of removing temporary and permanent hardness from water.”
Pupils’ Activity: Pupils listen to the summary and copy the assignment.
Learning Point: Pupils consolidate their understanding of the topic and prepare for future learning.

Lesson Keywords

Water – A clear, colourless, odourless, and tasteless liquid essential for life.
Soft Water – Water that readily forms lather with soap.
Hard Water – Water that does not readily form lather with soap due to dissolved mineral salts.
Temporary Hardness – Water hardness caused by dissolved bicarbonates of calcium and magnesium.
Permanent Hardness – Water hardness caused by dissolved sulphates and chlorides of calcium and magnesium.
Pollutant – A substance that contaminates water, making it impure or unsafe.
Lather – Froth or foam produced when soap is mixed with water.

Differentiation

For pupils who grasp concepts quickly, the teacher can encourage them to research advanced water treatment methods or the environmental impact of specific pollutants. For pupils needing more support, the teacher can provide simplified diagrams, extra explanations, or pair them with higher-achieving peers during practical activities.

Note for teachers using this lesson plan

Ensure all safety precautions are observed when handling water samples, especially if demonstrating with contaminated water. Encourage pupils to relate the lesson content to their local environment and daily experiences to enhance relevance and understanding.