Week Three
Subject: Physical And Health Education
Class: Primary Two
Week of the Third Term: 3rd Week
Topic: Methods of Purifying Water (Continued)
Subtopic: Chemical Treatment and Sieving
Instructional Objectives
At the end of the lesson, pupils should be able to:
- Describe the process of chemical treatment in purifying water and identify common chemicals used.
- Explain how sieving works and its role in removing larger impurities from water.
- Demonstrate how to properly perform chemical treatment and sieving of water.
Entry Behaviour
Pupils should have prior knowledge of the basic methods of purifying water, including filtration and boiling.
Instructional Materials
- Chemicals for treatment (e.g., chlorine tablets or iodine) and clear demonstration of usage
- Sieving materials (e.g., a sieve or cloth) to demonstrate the sieving process
- Visual aids: Posters or charts showing the chemical treatment and sieving processes
Reference Materials
Baba Gbefwi, N., Okoroigwe, E., & Akinmorin, A. (2017). Wabp Physical and Health Education for Primary Schools Book 2. Lagos: West African Book Publisher.
Adeyanju, S. A., Danladi, M. I., Edegbai, B., Igbanu, V. C., & Okunrotifa, E. B. (2022). Spectrum Physical and Health Education for Primary School 2 Textbook (BEC Edition). Lagos: Spectrum Book Limited.
Content
Methods of Purifying Water (Continued): Chemical Treatment and Sieving
Why Purify Water?
Purifying water is important because it helps remove harmful substances, making it safe to drink. Two additional methods for purifying water are chemical treatment and sieving.
1. Chemical Treatment
What is Chemical Treatment?
Chemical treatment involves adding substances to water to kill germs and make it safe to drink. These chemicals can help disinfect the water, removing harmful bacteria and viruses.
Common Chemicals Used:
- Chlorine: A popular chemical used to kill bacteria and viruses in water. Chlorine is often added to drinking water supplies.
- Iodine: Another chemical that can be used in small amounts to purify water, especially in emergency situations or when camping.
How Does It Work?
- Step 1: A small amount of the chemical (like chlorine) is added to the water.
- Step 2: The water is mixed and allowed to sit for a while. This gives the chemical time to work and kill any harmful germs.
Benefits of Chemical Treatment:
- It effectively kills germs that cause diseases.
- It can make large amounts of water safe quickly.
2. Sieving
What is Sieving?
Sieving is a method that uses a sieve (a tool with small holes) to separate solid particles from liquids. This method is useful for removing larger impurities from water.
How Does It Work?
- Step 1: Water is poured through a sieve or a cloth with small holes.
- Step 2: The larger particles, dirt, and debris are caught in the sieve while the clean water passes through.
Benefits of Sieving:
- It helps remove visible impurities and larger particles from the water.
- It is a simple and quick way to clean water before further purification methods.
When to Use Sieving:
Sieving is often the first step before using other purification methods like boiling or chemical treatment. It prepares the water by removing larger particles, making the subsequent purification steps more effective.
Lesson Presentation (Step-by-Step Procedure)
Step 1: Introduction
Start by asking pupils, “What do we do if we find dirty water?” Share an interesting fact about how chemicals can help make water safe.
Step 2: Explanation
Explain the two methods of purifying water: chemical treatment and sieving. Use examples from their surroundings to illustrate these methods.
Step 3: Demonstration
Demonstrate how to perform chemical treatment by showing how to add chlorine or iodine to a small amount of water. Also, demonstrate sieving using a sieve or cloth to filter out larger particles from dirty water.
Step 4: Guided Practice
In small groups, have pupils practice the sieving process with water and dirt. Ensure they understand how to correctly use the sieve and the importance of this step in cleaning water.
Step 5: Independent Practice
Ask pupils to write a few sentences about the role of chemical treatment or sieving in purifying water, using simple language.
Step 6: Feedback
Provide feedback on their written sentences, encouraging them to ask questions or share thoughts about water purification methods.
Evaluation
Formative Assessment:
Observe pupils during the sieving activity to assess their understanding of how sieving works and ensure they can identify the materials used for chemical treatment.
Summative Assessment:
At the end of the lesson, give a short quiz asking questions about chemical treatment and sieving, checking for understanding of these purification methods.
Summary/Conclusion
Summarize the importance of purifying water and the methods discussed: chemical treatment for killing germs and sieving for removing large particles. Encourage pupils to ask any remaining questions.
Assignment
Instruct pupils to research one chemical used in water treatment and to draw a picture of the sieving process at home or in the classroom.