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Subject: Biology
Semester: 2
Period: 6
Week: 34
School Name:
Teacher’s Name:
Subject: Biology
Grade Level: Grade 12
Week & Period: Week 34, Period VI
Date:
Topic: Sewage Disposal and Water Purification
Sub-topic: Sewage Definition, Methods and Economic Uses; Water Sources, Contamination and Purification
Learning Objectives
By the end of the lesson, learners should be able to:
- Define sewage and sewage disposal.
- Describe methods of sewage disposal and identify their importance.
- List economic uses of sewage.
- Identify the sources and types of water contamination.
- Explain basic methods of water purification.
Previous Knowledge
Learners have discussed sanitation, community hygiene, and the importance of clean environments in previous weeks. They understand that diseases can spread through water and poor waste handling.
Instructional Materials
- Diagram of a sewage system
- Water filter model (DIY or illustrated)
- Pictures or videos of waterborne diseases and their sources
- Chart showing before-and-after effects of sewage treatment
Anticipation (Warm-Up) – 5 minutes
Ask:
💬 “Where does your poop go after you flush?”
💬 “Have you ever seen dirty water flow through your street?”
Use these questions to start a conversation about the importance of managing waste and keeping water clean.
Building Knowledge (Main Lesson) – 25 minutes
- Sewage and Sewage Disposal
- Sewage is wastewater from homes, schools, and factories that contains human waste, food particles, soap, etc.
- Sewage Disposal means removing and treating waste safely.
Methods of Sewage Disposal:
- Pit latrines
- Septic tanks
- Sewage treatment plants
- Use of chemicals (chlorination)
Economic Uses of Treated Sewage:
- Fertilizer for farming (manure)
- Biogas production
- Irrigation
- Land reclamation
- Water: Sources, Contamination & Purification
Sources of Water:
- Rainwater, wells, rivers, lakes, taps
Modes of Water Contamination:
- Animal/human waste
- Factory discharge
- Pesticides and fertilizers
- Garbage dumping
Water Purification Methods:
- Boiling
- Filtration (sand and gravel)
- Chlorination
- Sunlight (solar disinfection/SODIS)
- Water purification tablets
Learners’ Activities
- Demonstrate how to make a simple water filter using sand and charcoal.
- Group brainstorm: “What should communities do with waste to protect rivers?”
- Role-play: team of health workers explaining safe water and sewage practices to a rural village.
Consolidation (Review and Assessment) – 10 minutes
Oral Questions:
- What is sewage?
- Name two methods of sewage disposal.
- Mention two ways water can become dirty.
- How can we make water safe to drink?
Short Notes (For Learners)
Sewage is dirty water from homes and factories. It must be removed and treated to keep the environment clean.
Sewage can be used to make fertilizer and fuel.
Water gets dirty through waste and chemicals. To make water safe, we can boil it, filter it, or use chemicals.
Expanded Notes/Instructions
- Use local examples of dirty gutters or rivers.
- If possible, organize a short tour of a school’s waste disposal setup.
- Discuss the cost of poor sanitation: e.g. cholera outbreaks, hospital bills.
Inclusive/Differentiation
- Visual learners: illustrations of water filters and sewage systems
- Kinesthetic learners: build a simple filter
- Group projects: “Design a sewage system for a small village”
Homework/Assignment
- Write 5 ways sewage can be used after treatment.
- List and explain any 3 methods of purifying drinking water.
- Interview someone in your neighborhood: “How do they dispose of dirty water?”