Class: Senior Secondary School 1 (SS1, SS 1, SSS1, SSS 1)
Term: 1st Term
Week: 8
Age: 15 years
Duration: 45 minutes
Subject: Metal Work
Curriculum Theme: Pre-Vocational Studies
Previous Lesson: Properties of Metals: Physical, Mechanical and Chemical.
Topic: Physical Properties of Metals
Subject Matter: Ductility of metals, Malleability of metals, Hardness of metals.

Specific Objectives

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

Cognitive Domain:

Define ductility, malleability, and hardness of metals.
Explain the importance of these properties in metal work.

Affective Domain:

Appreciate the significance of understanding metal properties.
Show interest in observing demonstrations of metal properties.

Psychomotor Domain:

Observe and describe simple demonstrations of scratching, cutting, hammering, and rolling.
Identify examples of ductile, malleable, and hard metals.

Work collaboratively during practical demonstrations.

Reference Materials

The following resources were used in planning this lesson:

9 Years Basic Education Curriculum for Pre-Vocational Studies (Metal Work).
State Unified Scheme of Work for Senior Secondary School Metal Work.
Akinwande, D.G. (2018). Metal Work for Senior Secondary Schools. Ibadan: University Press PLC.
https://www.engineeringtoolbox.com/metal-properties-d_25.html
https://www.britannica.com/science/ductility

Instructional Materials

The teacher will teach this lesson with the aid of:

Mild steel plate
Hacksaw blade
Hammer
File
Samples of malleable metals (e.g., aluminium sheet, copper sheet)
Samples of ductile metals (e.g., copper wire, aluminium wire)

Rationale for the Lesson

Understanding the physical properties of metals like ductility, malleability, and hardness helps pupils choose the right metal for specific applications in everyday life and in metal fabrication. This knowledge enables pupils to predict how different metals will behave when worked on, which is important for safety and quality in practical metalwork.

Prerequisite/Previous Knowledge

Pupils are assumed to have prior knowledge of basic hand tools and some general characteristics of materials from previous lessons.

Lesson Content/Board Summary

Physical Properties of Metals

1. Hardness

Hardness is the ability of a metal to resist scratching, indentation, or abrasion. Hard metals are difficult to cut, scratch, or deform permanently.

Demonstrations of hardness involve:

Scratching one metal against another.
Using a cutting tool (e.g., hacksaw blade, file) to remove material from a metal surface.

Examples of hard metals include high carbon steel and cast iron.

2. Malleability

Malleability is the ability of a metal to be permanently deformed under compression (e.g., by hammering or rolling) without fracturing or breaking. Malleable metals can be flattened into thin sheets.

Demonstrations of malleability involve:

Hammering a metal sample to flatten it.
Rolling a metal sheet to reduce its thickness.

Examples of malleable metals include gold, silver, copper, and aluminium.

3. Ductility

Ductility is the ability of a metal to be drawn out into a thin wire without losing its strength or fracturing. Ductile metals can be stretched or elongated under tension.

Examples of ductile metals are:

Copper (commonly used for electrical wires).
Aluminium.
Mild steel.

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 then introduces the new topic by asking pupils if they know why some metals are used for making wires while others are used for making hammers.
Pupils’ Activity: Pupils respond to questions and listen attentively to the introduction.
Learning Point: Pupils are prepared for the day’s lesson and connect new knowledge with previous learning.

Step 2: Explanation and Demonstration of Hardness

Time: 10 minutes
Teaching Skill: Demonstration/Explanation
Teacher’s Activity: The teacher defines hardness and demonstrates it by trying to scratch a mild steel plate with a hacksaw blade or a file. The teacher explains that the resistance to scratching shows the metal’s hardness.
Pupils’ Activity: Pupils observe the demonstration carefully and ask questions for clarification.
Learning Point: Pupils understand the meaning of hardness and how it can be demonstrated.

Step 3: Explanation and Demonstration of Malleability

Time: 10 minutes
Teaching Skill: Demonstration/Explanation
Teacher’s Activity: The teacher defines malleability. Using a hammer, the teacher demonstrates malleability by hammering a small piece of malleable metal (e.g., aluminium or copper sheet) to flatten it. The teacher explains that the metal changes shape without breaking.
Pupils’ Activity: Pupils observe the hammering process and note how the metal deforms.
Learning Point: Pupils understand malleability and observe its practical demonstration.

Step 4: Explanation of Ductility

Time: 7 minutes
Teaching Skill: Explanation/Discussion
Teacher’s Activity: The teacher defines ductility and provides examples of ductile metals like copper and aluminium, explaining their use in making wires. The teacher may show a copper wire as an example.
Pupils’ Activity: Pupils listen, observe the wire sample, and contribute to the discussion by mentioning other ductile materials they know.
Learning Point: Pupils grasp the concept of ductility and its common applications.

Step 5: Importance of Metal Properties

Time: 5 minutes
Teaching Skill: Discussion/Application
Teacher’s Activity: The teacher leads a discussion on why it is important to know these properties when choosing metals for different uses (e.g., a hard metal for tools, a malleable metal for body panels, a ductile metal for electrical wiring).
Pupils’ Activity: Pupils share their ideas on the practical importance of these properties.
Learning Point: Pupils understand the real-world application of the physical properties of metals.

Step 6: Class Activity/Review

Time: 3 minutes
Teaching Skill: Questioning/Consolidation
Teacher’s Activity: The teacher asks pupils to briefly describe each property (hardness, malleability, ductility) in their own words, giving an example for each.
Pupils’ Activity: Pupils orally describe the properties and provide examples.
Learning Point: Pupils consolidate their understanding of the lesson content.

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 ductility.
What is malleability?
State two ways to demonstrate the hardness of a metal.
Mention an example of a ductile metal.

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 key points of the lesson on the physical properties of metals and assigns homework: “List five metals and state one physical property for each.”
Pupils’ Activity: Pupils copy the homework and prepare for the next subject.
Learning Point: Pupils recall the main concepts and are given an opportunity to reinforce their learning.

Lesson Keywords

Hardness – The ability of a metal to resist scratching, indentation, or abrasion.
Malleability – The ability of a metal to be permanently deformed under compression (hammering or rolling) without breaking.
Ductility – The ability of a metal to be drawn out into a thin wire without fracturing.

Differentiation

For pupils who grasp concepts quickly, the teacher can encourage them to research other physical properties of metals not covered in the lesson. For pupils who require more support, the teacher can provide additional examples and visual aids, or pair them with peers for collaborative learning during demonstrations.

Note for teachers using this lesson plan

Ensure all demonstration materials are readily available and safe to use before the lesson. Emphasize safety precautions during demonstrations involving hammers or sharp tools. Encourage pupils to actively participate and ask questions to deepen their understanding of these fundamental metal properties.