Class: Senior Secondary School 1 (SS1 / SSS1)
Term: 2nd Term
Week: 10
Age: 15 years
Duration: 45 minutes
Subject: Furniture Making
Curriculum Theme: Trade
Previous Lesson: Defect In Timber: Types And Causes.
Topic: Preservation Of Timber
Subject Matter: Meaning of timber preservation, Characteristics of good preservatives, Application methods

Specific Objectives

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

Cognitive Domain:

Define timber preservation.
List at least three characteristics of good timber preservatives.
Mention at least two methods of applying timber preservatives.

Affective Domain:

Appreciate the importance of preserving timber.
Show interest in learning about different types of preservatives.

Psychomotor Domain:

Identify treated timber.
Demonstrate the brushing method of preservative application.

Participate in class discussions on timber preservation.
Collaborate with peers to identify suitable preservatives for different timber uses.

Reference Materials

The following resources were used in planning this lesson:

9 Years Basic Education Curriculum for Furniture Making.
State Unified Scheme of Work for Senior Secondary Schools.
Furniture Making for Senior Secondary Schools, Book 1.
FURNITURE MAKING SSS CURRICULUM
FURNITURE MAKING JSS SSS

Instructional Materials

The teacher will teach this lesson with the aid of:

A paint brush
A can of wood preservative
Samples of treated and untreated timber

Rationale for the Lesson

This lesson helps pupils understand how to protect timber from damage, which is important for making furniture that lasts long. Learning about preservation methods enables pupils to extend the lifespan of wooden products and save resources.

Prerequisite/Previous Knowledge

Pupils are expected to have prior knowledge of different types of timber and their various uses in furniture making.

Lesson Content/Board Summary

Preservation of Timber

Meaning of Timber Preservation

Timber preservation is the process of treating timber to protect it from agents of decay such as fungi, insects (termites, borers), and adverse weather conditions. This treatment helps to extend the useful life of timber and maintain its strength and appearance.

Characteristics of Good Preservatives

A good timber preservative should possess the following characteristics:

It must be effective against a wide range of fungi and insects.
It should be non-toxic to humans and animals after application and drying.
It should not be corrosive to metals that may be in contact with the treated timber.
It must be able to penetrate the timber easily and deeply.
It should not significantly alter the natural appearance, strength, or workability of the timber.
It should be long-lasting and provide durable protection.
It must be economical and readily available.
It should be safe to handle during application.

Methods of Applying Timber Preservatives

The following are common methods for applying preservatives to timber:

Brushing: This involves applying the preservative directly to the timber surface using a brush. It is suitable for small areas and timber not exposed to severe conditions.
Spraying: Preservatives can be applied using a spray gun, which provides a more even coating over larger surfaces than brushing.
Dipping: Timber is immersed in a tank containing the preservative for a specific period. This method ensures better overall coverage and some penetration.
Hot and Cold Open Tank Process: Timber is first heated in a tank of preservative, then allowed to cool while still submerged. The cooling causes the preservative to be drawn deeper into the timber cells.
Pressure Impregnation (Vacuum-Pressure Process): This is the most effective method, where timber is placed in a sealed cylinder. Air is first removed (vacuum), then the preservative is introduced under high pressure, forcing it deep into the wood structure.

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 to recall what they learned about different types of timber in the previous lesson. The teacher then introduces the topic by asking why it is important to protect wood from damage.
Pupils’ Activity: Pupils respond to the questions and listen attentively to the introduction of the new topic.
Learning Point: Pupils are reminded of previous knowledge and introduced to the concept of timber protection.

Step 2: Meaning of Timber Preservation

Time: 8 minutes
Teaching Skill: Explanation/Definition
Teacher’s Activity: The teacher explains the meaning of timber preservation, emphasizing the importance of protecting timber from decay, insects, and fungi to extend its life. The teacher writes the definition on the board.
Pupils’ Activity: Pupils listen, take notes, and ask questions for clarification.
Learning Point: Pupils understand the definition and purpose of timber preservation.

Step 3: Characteristics of Good Preservatives

Time: 10 minutes
Teaching Skill: Listing/Elaboration
Teacher’s Activity: The teacher discusses the key characteristics of good timber preservatives, such as effectiveness, non-toxicity, non-corrosiveness, and good penetration. The teacher lists these characteristics on the board.
Pupils’ Activity: Pupils listen, contribute examples if any, and copy notes from the board.
Learning Point: Pupils can identify the qualities of effective timber preservatives.

Step 4: Methods of Applying Timber Preservatives

Time: 10 minutes
Teaching Skill: Demonstration/Explanation
Teacher’s Activity: The teacher explains and demonstrates (using a paint brush and a can of wood preservative) the various methods of applying preservatives, including brushing, spraying, dipping, and briefly explaining the hot and cold tank and pressure methods. The methods are listed on the board.
Pupils’ Activity: Pupils observe the demonstration, ask questions, and take notes.
Learning Point: Pupils learn about different techniques for applying timber preservatives.

Step 5: Identification of Treated Timber

Time: 5 minutes
Teaching Skill: Observation/Identification
Teacher’s Activity: The teacher presents samples of treated and untreated timber, guiding pupils to observe and identify differences in appearance or texture that indicate preservation.
Pupils’ Activity: Pupils examine the timber samples and discuss their observations.
Learning Point: Pupils can visually identify treated timber.

Step 6: Class Discussion/Q&A

Time: 2 minutes
Teaching Skill: Facilitation/Questioning
Teacher’s Activity: The teacher facilitates a brief discussion, allowing pupils to ask any remaining questions and clarify difficult points from the lesson.
Pupils’ Activity: Pupils ask questions and participate in the discussion.
Learning Point: Pupils consolidate their understanding through interaction.

Step 7: Evaluation/Review

Time: 5 minutes

Teaching Skill: Questioning/Assessment

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

What is timber preservation?
State three characteristics of a good timber preservative.
Mention two methods used to apply preservatives to timber.
Why is it important to preserve timber?

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/Assignment
Teacher’s Activity: The teacher summarizes the main points of the lesson, reiterating the importance of timber preservation. The teacher assigns homework: find out about different types of wood preservatives available in the market.
Pupils’ Activity: Pupils listen to the summary and write down the homework.
Learning Point: Pupils review the lesson and receive a task for further learning.

Lesson Keywords

Preservation – The act of keeping something in its original state or in good condition.
Timber – Wood prepared for use in building and carpentry.
Preservative – A substance used to protect something from decay.
Decay – The process of rotting or decomposition caused by fungi or bacteria.
Fungi – Organisms like mushrooms or moulds that can cause wood to rot.
Termites – Social insects that feed on wood, causing significant damage.

Differentiation

For pupils who grasp concepts quickly, the teacher can encourage them to research specific types of timber preservatives (e.g., creosote, copper chrome arsenate) and their applications. For pupils needing more support, the teacher will provide simplified explanations and more direct guidance during the demonstration and question-and-answer sessions.

Note for teachers using this lesson plan

Teachers should ensure that actual samples of treated and untreated timber are available for pupils to observe. If a real demonstration of preservative application is not feasible due to safety or resource constraints, a video or detailed step-by-step pictorial guide should be used. Emphasize safety precautions when handling wood preservatives.