Class: Senior Secondary School 1 (SS1, SS 1, SSS1, SSS 1)
Term: 3rd Term
Week: 8
Age: 15 years
Duration: 45 minutes
Subject: Auto Mechanic Work
Curriculum Theme: Auto Mechanic Work
Previous Lesson: Fuel System Components: Pump, Carburetor and Float Chamber.
Topic: MANIFOLD – Functions and Types
Subject Matter: function of manifold, inlet manifold, exhaust manifold, removal and replacement of manifold, identification of manifold types

Specific Objectives

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

Cognitive Domain:

Define a manifold in an internal combustion engine.
State at least two functions of a manifold.
Identify and differentiate between an inlet manifold and an exhaust manifold.

Affective Domain:

Appreciate the importance of manifolds in engine performance.
Show interest in the practical aspects of auto mechanic work.

Psychomotor Domain:

Demonstrate the proper procedure for removing a manifold.
Demonstrate the proper procedure for replacing a manifold.

Work cooperatively during practical demonstrations and discussions.

Reference Materials

The following resources were used in planning this lesson:

9 Years Basic Education Curriculum for Auto Mechanic Work.
State Unified Scheme of Work for Senior Secondary Schools.
Auto Mechanic Work for Senior Secondary Schools, Book 1.

Instructional Materials

The teacher will teach this lesson with the aid of:

Actual manifolds (inlet and exhaust).
Charts showing engine components.
Posters illustrating manifold types and their locations.
A live vehicle or engine model for demonstration.

Rationale for the Lesson

This lesson helps pupils understand important components of an internal combustion engine. Knowing about manifolds and their functions is essential for diagnosing engine problems and performing basic maintenance, which is valuable for their future in auto mechanics.

Prerequisite/Previous Knowledge

Pupils have basic knowledge of the internal combustion engine and its main components such as the cylinder head and exhaust system.

Lesson Content/Board Summary

MANIFOLD – Functions and Types

Definition of Manifold

A manifold is a component of an internal combustion engine that directs the flow of gases to and from the engine cylinders.

Functions of a Manifold

The main functions of a manifold are:

To distribute the air-fuel mixture (or air only in direct injection engines) evenly to the engine cylinders.
To collect and channel exhaust gases from the engine cylinders to the exhaust system.

Types of Manifold

Inlet Manifold

The inlet manifold (also known as intake manifold) is responsible for distributing the air-fuel mixture (or air) from the carburettor/throttle body to each cylinder.

The following are characteristics and functions of an inlet manifold:

It is usually made of aluminium alloy or plastic to reduce weight and aid in cooling.
It is designed with runners of specific lengths and shapes to optimize airflow and fuel atomisation.
Its primary function is to ensure an equal amount of air-fuel mixture reaches each cylinder for efficient combustion.

Exhaust Manifold

The exhaust manifold collects the hot exhaust gases from each cylinder after combustion and directs them into a single pipe, leading to the exhaust system.

The following are characteristics and functions of an exhaust manifold:

It is typically made of cast iron or stainless steel due to the high temperatures of exhaust gases.
Its design aims to reduce back pressure and allow for efficient removal of gases from the cylinders.
Its primary function is to channel toxic exhaust gases away from the engine and vehicle occupants safely.

Removal and Replacement of Manifold

The process of removing and replacing a manifold generally involves the following steps:

Disconnect the vehicle’s battery to prevent electrical hazards.
Drain engine coolant (if the manifold is water-cooled).
Remove any attached components like the air intake system, oxygen sensors, or exhaust pipes.
Unbolt the manifold from the cylinder head, ensuring to follow proper loosening sequences.
Clean the mating surfaces on both the manifold and cylinder head thoroughly.
Install a new manifold gasket to ensure a proper seal.
Position the manifold and tighten the bolts to the manufacturer’s specified torque and sequence.
Reconnect all previously removed components.
Refill engine coolant and reconnect the battery.

Identification of Manifold Types

Manifolds can be identified by their location on the engine and the systems they connect to. The inlet manifold is connected to the air filter and often the fuel system, while the exhaust manifold is connected to the exhaust pipe leading to the muffler.

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 reviews the previous lesson briefly. The teacher then asks pupils what they think happens to air entering the engine and gases leaving the engine. This leads to introducing the topic of manifolds.
Pupils’ Activity: Pupils respond to questions and listen attentively.
Learning Point: Pupils are prepared for the new lesson and relate it to prior knowledge.

Step 2: Definition and Functions of Manifold

Time: 10 minutes
Teaching Skill: Explanation/Illustration
Teacher’s Activity: The teacher defines a manifold and explains its general functions using charts and a live engine/model. The teacher emphasizes why manifolds are important for engine operation.
Pupils’ Activity: Pupils listen, observe the charts and vehicle, and ask questions for clarity.
Learning Point: Pupils understand what a manifold is and its overall purpose.

Step 3: Types of Manifold (Inlet Manifold)

Time: 8 minutes
Teaching Skill: Demonstration/Explanation
Teacher’s Activity: The teacher explains the inlet manifold, its specific functions, characteristics, and shows an actual inlet manifold or points it out on the live vehicle. The teacher uses diagrams to illustrate airflow.
Pupils’ Activity: Pupils observe the actual manifold, diagrams, and listen to the explanation. They may identify the inlet manifold on the vehicle.
Learning Point: Pupils can identify an inlet manifold and state its functions.

Step 4: Types of Manifold (Exhaust Manifold)

Time: 8 minutes
Teaching Skill: Demonstration/Explanation
Teacher’s Activity: The teacher explains the exhaust manifold, its specific functions, characteristics, and shows an actual exhaust manifold or points it out on the live vehicle. The teacher highlights the differences between inlet and exhaust manifolds.
Pupils’ Activity: Pupils observe the actual manifold, compare it with the inlet manifold, and listen to the explanation.
Learning Point: Pupils can identify an exhaust manifold and state its functions, and differentiate it from an inlet manifold.

Step 5: Removal and Replacement Demonstration

Time: 7 minutes
Teaching Skill: Practical Demonstration
Teacher’s Activity: The teacher demonstrates the basic steps involved in the removal and replacement of a manifold using the live vehicle or a detached engine component. Emphasis is placed on safety and correct procedures.
Pupils’ Activity: Pupils carefully observe the demonstration and note the steps and safety precautions.
Learning Point: Pupils understand the practical steps for manifold removal and replacement.

Step 6: Identification of Manifold Types

Time: 2 minutes
Teaching Skill: Practical Application
Teacher’s Activity: The teacher asks pupils to identify the inlet and exhaust manifolds on the live vehicle or from diagrams, reinforcing their understanding.
Pupils’ Activity: Pupils actively participate in identifying the different types of manifolds.
Learning Point: Pupils confidently identify different manifold types in a practical context.

Step 7: Evaluation/Review

Time: 3 minutes

Teaching Skill: Questioning/Assessment

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

Define a manifold in an internal combustion engine.
State two functions of an inlet manifold.
Mention two differences between an inlet manifold and an exhaust manifold.
List three steps involved in the removal of an exhaust manifold.

Pupils’ Activity: Pupils answer orally and in writing.

Learning Point: Pupils demonstrate understanding of the lesson.

Step 8: Conclusion

Time: 2 minutes
Teaching Skill: Summarization
Teacher’s Activity: The teacher summarizes the key learning points about manifolds, their types, functions, and the importance of proper handling during removal and replacement. The teacher assigns homework: “Draw and label an inlet and an exhaust manifold, highlighting their connection points.”
Pupils’ Activity: Pupils listen to the summary, ask any final questions, and copy down the homework.
Learning Point: Pupils consolidate their learning and prepare for further study.

Lesson Keywords

Manifold – A pipe fitting that branches into several openings, used to collect or distribute fluids or gases.
Inlet Manifold – Part of the engine that supplies the air-fuel mixture to the cylinders.
Exhaust Manifold – Part of the engine that collects exhaust gases from the cylinders.
Gasket – A mechanical seal that fills the space between two or more mating surfaces, generally to prevent leakage.

Differentiation

For pupils who grasp concepts quickly, the teacher will encourage them to research different manifold designs (e.g., tuned manifolds, variable intake manifolds) and their impact on engine performance. For pupils needing more support, the teacher will provide additional diagrams and one-on-one guidance during practical identification, focusing on the core definitions and functions.

Note for teachers using this lesson plan

Ensure all safety precautions are observed during the practical demonstration, especially when working with a live vehicle or engine. Emphasize the importance of using correct tools and following manufacturer specifications for torque settings during manifold replacement. Encourage pupils to ask questions and actively participate in discussions to enhance their understanding of these critical engine components.