Class: Senior Secondary School 1 (SS1, SS 1, SSS1, SSS 1)
Term: 1st Term
Week: 10
Age: 15 years
Duration: 45 minutes
Subject: Metal Work
Curriculum Theme: Pre-Vocational Studies
Previous Lesson: Production of Metals: Sources and Extraction Methods.
Topic: Metal Production Processes
Subject Matter: Bessemer Process, Open Hearth Furnace, Reverberatory Furnace, Principles of Furnace Operation, Basic Methods used in Manufacturing Processes.

Specific Objectives

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

Cognitive Domain:

Define the Bessemer process, Open Hearth furnace, and Reverberatory furnace.
Explain the operating principles of each furnace.
State the basic methods used in manufacturing processes.

Affective Domain:

Appreciate the importance of these processes in metal production.
Develop interest in the field of metal work.

Psychomotor Domain:

Label sketches of different furnaces.
Summarize the working principle of each process.

Participate in class discussions on metal production processes.

Reference Materials

The following resources were used in planning this lesson:

9 Years Basic Education Curriculum for Senior Secondary Schools.
State Unified Scheme of Work for Senior Secondary Schools.
Metalwork Technology for Senior Secondary Schools by E.A. Adedipe.

Instructional Materials

The teacher will teach this lesson with the aid of:

Furnace charts
Board sketches of furnaces
Process flow diagrams for metal production
Whiteboard/Chalkboard
Markers/Chalk

Rationale for the Lesson

This lesson helps pupils understand how common metal products are made from raw materials through various industrial processes. It enables them to appreciate the technological methods involved in transforming raw metals into usable forms for daily life.

Prerequisite/Previous Knowledge

Pupils should have basic knowledge of different types of metals and their general properties.

Lesson Content/Board Summary

Production of Metals

Introduction to Metal Production

Metal production involves extracting metals from their ores and refining them into usable forms. Various processes are used depending on the type of metal and desired purity.

Bessemer Process for Steel Production

The Bessemer process is the first inexpensive industrial process for the mass-production of steel from molten pig iron. It involves blowing air through molten pig iron to oxidize impurities.

Key characteristics of the Bessemer process:

Uses a pear-shaped converter lined with refractory material.
Air is blown through tuyeres at the bottom of the converter.
Oxidizes impurities like silicon, manganese, and carbon.
Produces steel quickly but requires careful control.

Open Hearth Furnace Method

The Open Hearth furnace is a regenerative furnace used for making steel. It can use a wide range of raw materials, including scrap metal and pig iron, making it more flexible than the Bessemer process.

Features of the Open Hearth furnace:

Operates at high temperatures, allowing for better impurity removal.
Uses a shallow hearth where the molten metal is exposed to hot gases.
Allows for precise control of the steel composition.
Takes longer to produce steel compared to the Bessemer process.

Reverberatory Furnace Method

A reverberatory furnace is a metallurgical furnace in which the flame and hot gases are separated from the material by a low wall, and the heat reflects down from the roof onto the material. It is often used for smelting non-ferrous metals like copper and tin.

Principles of the Reverberatory furnace:

Heat is radiated from the roof and sidewalls, not directly from the flame.
Prevents direct contact between the fuel and the charge.
Allows for controlled atmospheric conditions within the furnace.
Suitable for materials that would be contaminated by direct flame contact.

Principles of Furnace Operation

Furnaces operate based on principles that ensure efficient heating and chemical reactions. These include:

Heat Transfer: Conduction, convection, and radiation are used to transfer heat to the charge.
Fuel Combustion: Controlled burning of fuel (e.g., coal, oil, gas) to generate high temperatures.
Refractory Lining: Use of heat-resistant materials to insulate the furnace and withstand high temperatures.
Atmospheric Control: Managing the gas composition inside the furnace to promote desired reactions or prevent oxidation.

Basic Methods Used in Manufacturing Processes

Manufacturing processes involve various techniques to shape and form materials. Common methods include:

Casting: Pouring molten material into a mold to solidify.
Forming: Shaping materials by plastic deformation (e.g., rolling, forging, bending).
Machining: Removing material to create desired shapes (e.g., turning, milling, drilling).
Joining: Connecting separate parts (e.g., welding, soldering, brazing).
Assembly: Putting together components to create a finished product.

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, reviews the previous lesson briefly, and introduces the new topic: “Metal Production Processes,” explaining its relevance to everyday life.
Pupils’ Activity: Pupils respond to greetings, recall previous knowledge, and listen attentively to the introduction.
Learning Point: Pupils connect new learning to prior knowledge and understand the purpose of the lesson.

Step 2: Explanation of Bessemer Process

Time: 10 minutes
Teaching Skill: Explanation/Demonstration
Teacher’s Activity: The teacher explains the Bessemer process for steel production, using furnace charts and board sketches to illustrate the converter and its operation. The teacher also highlights the characteristics of the process.
Pupils’ Activity: Pupils listen, observe the charts, ask questions for clarification, and take notes.
Learning Point: Pupils understand the definition and key features of the Bessemer process.

Step 3: Explanation of Open Hearth Furnace Method

Time: 10 minutes
Teaching Skill: Explanation/Visualisation
Teacher’s Activity: The teacher explains the Open Hearth furnace method, describing its structure, operation, and advantages over the Bessemer process, using visual aids.
Pupils’ Activity: Pupils listen, study the diagrams, and make comparisons between the processes discussed.
Learning Point: Pupils understand the Open Hearth furnace method and its operational principles.

Step 4: Explanation of Reverberatory Furnace Method

Time: 7 minutes
Teaching Skill: Explanation/Illustration
Teacher’s Activity: The teacher describes the Reverberatory furnace, focusing on its design where the flame does not directly contact the material, and its common uses for non-ferrous metals.
Pupils’ Activity: Pupils pay attention, identify the unique features of the Reverberatory furnace, and take notes.
Learning Point: Pupils understand the Reverberatory furnace method and its principles.

Step 5: Principles of Furnace Operation

Time: 5 minutes
Teaching Skill: Elucidation
Teacher’s Activity: The teacher discusses general principles common to furnace operations, such as heat transfer, fuel combustion, refractory lining, and atmospheric control.
Pupils’ Activity: Pupils contribute to the discussion, ask questions, and note down the key principles.
Learning Point: Pupils grasp the fundamental principles guiding furnace operations.

Step 6: Basic Methods Used in Manufacturing Processes

Time: 3 minutes
Teaching Skill: Listing/Explanation
Teacher’s Activity: The teacher briefly lists and explains basic methods used in manufacturing processes, such as casting, forming, machining, and joining.
Pupils’ Activity: Pupils listen and note down the different manufacturing methods.
Learning Point: Pupils identify various basic manufacturing processes.

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 the Bessemer process for steel production.
List two characteristics of the Open Hearth furnace method.
Explain how a Reverberatory furnace operates.
Mention two basic principles of furnace operation.
State two basic methods used in manufacturing processes.

Pupils’ Activity: Pupils answer orally and in writing.

Learning Point: Pupils demonstrate understanding of the lesson.

Step 8: Conclusion

Time: 5 minutes
Teaching Skill: Summarization/Consolidation
Teacher’s Activity: The teacher summarizes the key points of the lesson, emphasizing the importance of different metal production processes. The teacher then assigns homework, asking pupils to research other types of furnaces used in metal production.
Pupils’ Activity: Pupils listen to the summary, ask any final questions, and copy down the homework.
Learning Point: Pupils consolidate their learning and are encouraged to explore further.

Lesson Keywords

Bessemer Process – An early industrial process for mass-producing steel from molten pig iron by blowing air through it.
Open Hearth Furnace – A regenerative furnace used for making steel, capable of using various raw materials including scrap.
Reverberatory Furnace – A furnace where the flame and charge are separated, with heat radiating from the roof onto the material.
Pig Iron – Crude iron, an intermediate product of smelting iron ore, containing a very high carbon content.
Steel – An alloy of iron with typically a few percent of carbon, used for construction and other applications.
Furnace – An enclosed structure in which material can be heated to very high temperatures.

Differentiation

For visual learners, detailed charts and board sketches will be used extensively. Auditory learners will benefit from clear explanations and discussions. Kinesthetic learners can participate by labeling furnace diagrams. Slower learners will receive additional guidance and simplified explanations, while advanced learners will be challenged with questions requiring deeper analysis of process efficiency and applications.

Note for teachers using this lesson plan

Teachers should ensure that all visual aids are clear and large enough for the entire class to see. Encourage pupils to ask questions and relate the processes to real-world metal products they encounter. Practical examples or short video clips, if available, can further enhance understanding of these industrial processes.