Class: Senior Secondary School 1 (SS1 / SSS 1)
Term: 1st Term
Week: 5
Age: 15 years
Duration: 45 minutes
Subject: Machine Wood Work
Curriculum Theme: Technology
Previous Lesson: Three Growth Structure And Types: Cross Section And Wood Sketches.
Topic: Properties of Timber
Subject Matter: Characteristics of softwood, Characteristics of hardwood, Physical properties of common West African timbers.

Specific Objectives

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

Cognitive Domain:

Define softwood and hardwood.
Differentiate between softwood and hardwood based on their characteristics.
List at least five physical properties of timber.
Identify examples of common West African timbers.

Affective Domain:

Appreciate the importance of understanding different timber properties in woodworking.
Show interest in observing and identifying various timber types.

Psychomotor Domain:

Handle and observe timber samples to identify their unique characteristics.
Categorise given timber samples into softwood and hardwood groups.

Participate actively in discussions about timber properties and uses.

Reference Materials

The following resources were used in planning this lesson:

9 Years Basic Education Curriculum for Basic Technology (JSS 1-3) and Senior Secondary Education Curriculum for Technical Drawing/Woodwork (SSS 1-3).
State Unified Scheme of Work for Senior Secondary School Woodwork.
Ayodele, S. O. (2010). Woodwork Technology for Senior Secondary Schools. Evans Brothers (Nigeria Publishers) Limited.

Instructional Materials

The teacher will teach this lesson with the aid of:

Samples of various softwood (e.g., pine, cedar) and hardwood (e.g., mahogany, iroko) timbers.
Charts illustrating properties of different timber types.
Hand lenses or magnifying glasses for close observation.

Rationale for the Lesson

Understanding the properties of different timbers helps pupils select the correct type of wood for specific woodworking projects. This knowledge is important for ensuring durability and functionality in their designs and for making informed decisions about materials in daily life.

Prerequisite/Previous Knowledge

Pupils should have a basic understanding of what timber is and its general uses from previous lessons.

Lesson Content/Board Summary

Properties of Timber

Characteristics of Softwood

Softwoods are timbers obtained from coniferous trees (cone-bearing trees with needles or scale-like leaves). These trees are typically evergreen and grow faster than hardwoods.

The following are characteristics of softwood:

Usually lighter in colour.
Generally less dense and lighter in weight.
Easier to work with hand tools and machines.
Has a simpler cell structure.
Growth rings are often more distinct.
Typically less durable and less resistant to decay than hardwoods.
Examples include Pine, Cedar, Spruce, Fir.

Characteristics of Hardwood

Hardwoods are timbers obtained from deciduous trees (broad-leaved trees that typically shed their leaves annually). These trees grow slower and are generally denser than softwoods.

The following are characteristics of hardwood:

Usually darker in colour, though some are light.
Generally denser and heavier in weight.
More difficult to work with hand tools and machines due to their hardness.
Has a more complex cell structure.
Growth rings are often less distinct.
Typically more durable and more resistant to decay than softwoods.
Examples include Mahogany, Iroko, Teak, Oak, Sapele.

Physical Properties of Common West African Timbers

Physical properties are observable characteristics of timber that can be used to identify and classify different wood types. These properties influence how timber behaves and its suitability for various applications.

The following are common physical properties of timber:

Colour: Varies widely (e.g., light brown of Obeche, reddish-brown of Mahogany, dark brown of Iroko).
Grain: Refers to the arrangement and direction of wood fibres. Can be straight, wavy, interlocked, spiral, etc.
Texture: Describes the fineness or coarseness of the wood fibres (e.g., fine, medium, coarse).
Odour: Some timbers have distinct smells, especially when freshly cut (e.g., aromatic Cedar, characteristic smell of Iroko).
Density/Weight: The amount of mass per unit volume. Denser timbers are generally heavier and stronger.
Hardness: Resistance to indentation or scratching. Harder timbers are more difficult to cut.
Durability: The ability of timber to resist decay, insect attack, and wear over time.
Lustre: The natural sheen or gloss of the wood surface.

Common West African timbers include Iroko, Mahogany, Obeche, Sapele, Teak, Mansonia, and Afzelia.

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 introduces the topic by asking them to recall different types of wood they have seen or used, and if they noticed any differences between them. The teacher then states the lesson topic: “Properties of Timber.”
Pupils’ Activity: Pupils respond to the teacher’s questions and listen attentively to the introduction.
Learning Point: Pupils recall prior knowledge and are introduced to the lesson topic.

Step 2: Characteristics of Softwood

Time: 8 minutes
Teaching Skill: Explanation/Demonstration
Teacher’s Activity: The teacher presents samples of softwood and explains their characteristics, such as origin from coniferous trees, lighter colour, lower density, and ease of working. The teacher encourages pupils to observe the samples closely.
Pupils’ Activity: Pupils observe the softwood samples, feel their texture, and listen to the teacher’s explanation. They may ask questions for clarification.
Learning Point: Pupils learn and identify the characteristics of softwood.

Step 3: Characteristics of Hardwood

Time: 8 minutes
Teaching Skill: Explanation/Demonstration
Teacher’s Activity: The teacher presents samples of hardwood and explains their characteristics, such as origin from deciduous trees, generally darker colour, higher density, and greater hardness. The teacher guides pupils to compare these with softwoods.
Pupils’ Activity: Pupils observe the hardwood samples, feel their texture, and compare them with softwood samples. They participate in discussions.
Learning Point: Pupils learn and identify the characteristics of hardwood.

Step 4: Differences between Softwood and Hardwood

Time: 5 minutes
Teaching Skill: Comparison/Discussion
Teacher’s Activity: The teacher facilitates a brief discussion to highlight the key differences between softwood and hardwood, summarising the points discussed in the previous steps.
Pupils’ Activity: Pupils contribute to the discussion by stating observed differences and consolidate their understanding.
Learning Point: Pupils can differentiate between softwood and hardwood.

Step 5: Physical Properties of Timber

Time: 8 minutes
Teaching Skill: Explanation/Illustration
Teacher’s Activity: The teacher explains various physical properties of timber, such as colour, grain, texture, odour, density, and durability, using the timber samples and property charts to illustrate each point.
Pupils’ Activity: Pupils observe the illustrations, listen to the explanations, and ask questions about the properties.
Learning Point: Pupils understand and can identify various physical properties of timber.

Step 6: Common West African Timbers

Time: 4 minutes
Teaching Skill: Naming/Identification
Teacher’s Activity: The teacher mentions and shows samples (if available) of some common West African timbers like Iroko, Mahogany, Obeche, and Sapele, briefly noting their general properties or uses.
Pupils’ Activity: Pupils identify the names and characteristics of common West African timbers.
Learning Point: Pupils are familiar with common West African timber types.

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 softwood and hardwood.
State three characteristics of softwood.
Mention three characteristics of hardwood.
List four physical properties of timber.
Name two common West African timbers.

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/Consolidation
Teacher’s Activity: The teacher summarises the key points of the lesson, reiterating the importance of understanding timber properties. The teacher assigns homework for pupils to research other common West African timbers and their uses.
Pupils’ Activity: Pupils listen to the summary and copy down the homework assignment.
Learning Point: Pupils consolidate their learning and are given further research tasks.

Lesson Keywords

Softwood – Timber from coniferous trees, generally lighter and easier to work.
Hardwood – Timber from deciduous trees, generally denser and harder to work.
Grain – The direction and arrangement of wood fibres.
Density – A measure of how heavy timber is for its size.
Durability – The ability of timber to resist decay and damage over time.
Iroko – A common West African hardwood known for its strength and durability.

Differentiation

For pupils who grasp concepts quickly, the teacher can challenge them to identify more complex timber properties like moisture content or shrinkage. For those needing more support, the teacher can provide simplified charts or focus on identifying only the most obvious characteristics of softwood and hardwood through hands-on practice with fewer samples.

Note for teachers using this lesson plan

Ensure a good variety of actual timber samples are available for pupils to touch, smell, and observe closely. Encourage active participation and group discussions during the identification of characteristics. Emphasise safety when handling timber samples, especially those with rough edges. Practical application of this knowledge in future woodworking projects should be highlighted.