Class: Senior Secondary School 1 (SS1, SS 1, SSS1, SSS 1)
Term: 3rd Term
Week: 9
Age: 15 years
Duration: 45 minutes
Subject: Building Construction
Curriculum Theme: Building Construction
Previous Lesson: Drainage System: Meaning, Terms and Types.
Topic: Drainage System: Drainage Layout and System Arrangement
Subject Matter: system of drainage, layout planning for drains, flow direction and slope, connection points and outlets, simple system sketches and descriptions

Specific Objectives

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

Cognitive Domain:

Define a drainage system.
Explain the principles of planning a drainage layout.
State the importance of correct flow direction and slope in drainage.
Identify common connection points and outlets in a drainage system.

Affective Domain:

Appreciate the importance of proper drainage for building hygiene and public health.
Show interest in drawing and interpreting drainage layouts.

Psychomotor Domain:

Sketch a simple drainage layout for a building.
Identify different components of a drainage system on a diagram.

Collaborate with peers in discussing various drainage system arrangements.

Reference Materials

The following resources were used in planning this lesson:

Senior Secondary Education Curriculum for Building Construction.
State Unified Scheme of Work for Senior Secondary School Building Construction.
Building Construction for Senior Secondary Schools by J.S. Okoro.

Instructional Materials

The teacher will teach this lesson with the aid of:

Actual drainage materials such as PVC pipes and fittings.
Example sketches and diagrams of drainage layouts.
Whiteboard or chalkboard and markers or chalk.

Rationale for the Lesson

This lesson helps pupils understand how waste water is removed from buildings and surrounding areas. Knowing about drainage systems is important for maintaining healthy living conditions and ensuring buildings function properly, preventing water damage and unsanitary environments.

Prerequisite/Previous Knowledge

Pupils have basic knowledge of water usage in buildings and may have observed pipe systems in their homes or schools.

Lesson Content/Board Summary

Drainage System: Drainage Layout and System Arrangement

Definition of Drainage System

A drainage system is a network of pipes, channels, and other structures designed to collect and convey wastewater (sewage and stormwater) away from buildings and areas to a disposal point, ensuring hygiene and preventing flooding.

Principles of Drainage Layout Planning

Effective drainage layout planning considers several factors to ensure efficient waste removal and system longevity. The following are principles for drainage layout planning:

Simplicity: The layout should be as simple and direct as possible to minimize blockages and maintenance.
Accessibility: All parts of the system, especially inspection chambers and clean-outs, should be easily accessible for maintenance and repairs.
Gradient/Slope: Pipes must have an adequate slope to allow wastewater to flow by gravity without stagnation or excessive velocity.
Ventilation: The system needs proper ventilation to prevent the build-up of foul gases and to ensure smooth flow.
Durability: Materials used should be durable and resistant to corrosion and wear.
Separate Systems: In many cases, separate systems for foul water (sewage) and surface water (stormwater) are used.

Flow Direction and Slope

Flow direction in a drainage system is always downwards, guided by gravity. The slope (gradient) of drainage pipes is critical for efficient operation. An insufficient slope leads to stagnation and blockages, while an excessive slope can cause solids to be left behind as water flows too quickly.

Typical slopes:

For 100mm diameter pipes, a slope of 1:40 to 1:80 is common.
For larger pipes, the slope can be less steep.

Connection Points and Outlets

Connection points are where various branch pipes join a main drain. Outlets are the final discharge points of the drainage system.

Common connection points and outlets include:

Gullies: Used to connect waste pipes from sinks, baths, and showers to the underground drainage system, often with a water seal.
Manholes/Inspection Chambers: Provide access for inspection, cleaning, and maintenance of the underground drainage system, especially at changes in direction or gradient.
Vent Pipes: Extend from the drainage system to above the roof level to provide ventilation and prevent siphonage.
Sewerage System: The main public or private network that collects wastewater from multiple buildings.
Soakaway Pit: A pit filled with rubble, allowing surface water to gradually percolate into the ground.
Septic Tank: For properties not connected to a public sewer, a tank that treats wastewater before discharge.

Simple Drainage System Sketches

A simple drainage layout sketch shows the arrangement of pipes, fittings, and access points from the building to the final discharge point. These sketches typically use standard symbols to represent different components.

Key elements to include in a sketch:

Building outline.
Location of sanitary fittings (WCs, sinks, baths).
Waste pipes connecting to gullies.
Underground drains showing direction of flow.
Inspection chambers/manholes.
Vent pipes.
Final discharge point (e.g., public sewer, septic tank).

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 what happens to water after it is used in the kitchen, bathroom, or toilet. The teacher then introduces the topic by explaining that this process is handled by a drainage system.
Pupils’ Activity: Pupils respond to the questions and listen attentively to the introduction.
Learning Point: Pupils recall prior knowledge and are introduced to the lesson topic.

Step 2: Explanation of Drainage System

Time: 8 minutes
Teaching Skill: Explanation/Definition
Teacher’s Activity: The teacher defines a drainage system and explains its purpose using simple language and practical examples. The teacher also shows examples of drainage pipes (PVC pipes) and fittings.
Pupils’ Activity: Pupils listen, take notes, and ask questions for clarification.
Learning Point: Pupils understand the definition and purpose of a drainage system.

Step 3: Discussion on Principles of Drainage Layout Planning

Time: 10 minutes
Teaching Skill: Discussion/Elaboration
Teacher’s Activity: The teacher explains the key principles involved in planning an effective drainage layout, such as simplicity, accessibility, gradient, and ventilation. The teacher uses diagrams to illustrate these principles.
Pupils’ Activity: Pupils participate in the discussion, contributing ideas and asking how these principles apply in real-life situations.
Learning Point: Pupils learn the essential guidelines for designing a functional drainage system.

Step 4: Explaining Flow Direction and Slope

Time: 7 minutes
Teaching Skill: Explanation/Demonstration
Teacher’s Activity: The teacher explains the concept of flow direction by gravity and the importance of maintaining the correct slope (gradient) for drainage pipes. The teacher may use a tilted pipe model to demonstrate the effect of different slopes.
Pupils’ Activity: Pupils observe the demonstration and understand how slope affects water flow.
Learning Point: Pupils grasp the significance of proper slope for efficient wastewater removal.

Step 5: Detailing Connection Points and Outlets

Time: 7 minutes
Teaching Skill: Identification/Description
Teacher’s Activity: The teacher identifies and describes various connection points (e.g., gullies, inspection chambers) and outlets (e.g., public sewer, septic tank) using diagrams and, if available, actual components. The teacher explains their function.
Pupils’ Activity: Pupils identify the components on diagrams and understand their roles in the system.
Learning Point: Pupils can name and describe different parts of a drainage system.

Step 6: Guiding on Simple Drainage System Sketches

Time: 5 minutes
Teaching Skill: Demonstration/Practical Application
Teacher’s Activity: The teacher demonstrates how to draw a simple drainage layout sketch on the board, explaining the symbols used for various components. The teacher guides pupils on what to include in their sketches.
Pupils’ Activity: Pupils observe the demonstration and attempt to sketch simple drainage layouts in their notebooks.
Learning Point: Pupils develop basic skills in sketching drainage layouts.

Step 7: Evaluation/Review

Time: 5 minutes

Teaching Skill: Questioning/Assessment

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

Define a drainage system.
Mention three principles of drainage layout planning.
Explain why the correct slope is important in drainage pipes.
List two common connection points in a drainage system.

Pupils’ Activity: Pupils answer orally and in writing.

Learning Point: Pupils demonstrate understanding of the lesson.

Step 8: Conclusion

Time: 3 minutes
Teaching Skill: Summarization/Assignment
Teacher’s Activity: The teacher summarizes the main points of the lesson, emphasizing the importance of well-designed drainage systems. The teacher then assigns homework: “Draw a simple drainage layout for a two-bedroom bungalow, showing the main components.”
Pupils’ Activity: Pupils listen to the summary and copy the homework assignment.
Learning Point: Pupils review the lesson content and receive an assignment to reinforce learning.

Lesson Keywords

Drainage System – A network of pipes and structures to remove wastewater.
Layout – The arrangement or design of components in a system.
Slope (Gradient) – The inclination of a pipe that allows water to flow by gravity.
Gully – A trapped fitting that connects waste pipes to the underground drain.
Inspection Chamber – An access point in an underground drainage system for inspection and cleaning.
Vent Pipe – A pipe that provides air to the drainage system to prevent siphonage and release foul gases.

Differentiation

For visual learners, the teacher will use many diagrams, real-life examples of pipes and fittings. For kinesthetic learners, pupils will be encouraged to sketch layouts and identify components on the physical materials. Struggling learners will receive additional guidance and simplified diagrams, while advanced learners can be challenged to design a more complex drainage system or research different types of drainage systems.

Note for teachers using this lesson plan

Teachers should ensure they have adequate visual aids, including actual pipe samples and clear diagrams, to effectively demonstrate the concepts of drainage layout and system arrangement. Encourage active participation and practical application through sketching. Emphasize safety precautions when discussing real-world drainage systems.