Class: Senior Secondary School 1 (SS1 / SSS 1)
Term: Second Term
Week: 8
Age: 15 years
Duration: 45 minutes
Subject: Furniture Making
Curriculum Theme: Trade
Previous Lesson: Seasoning Of Timber: Meaning And Benefits.
Topic: Methods Of Seasoning Timber
Subject Matter: Air seasoning, Kiln seasoning, Moisture reduction process

Specific Objectives

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

Cognitive Domain:

Instructional Materials

The teacher will teach this lesson with the aid of:

Charts showing diagrams of timber stacks for air seasoning.
Charts showing diagrams of a kiln dryer.
Samples of seasoned and unseasoned timber.
Whiteboard and markers.

Rationale for the Lesson

This lesson helps pupils understand why timber must be treated to reduce its moisture content. Learning about seasoning methods enables pupils to appreciate how timber is prepared for furniture making and other construction uses, which prevents warping and increases durability.

Prerequisite/Previous Knowledge

Pupils have basic knowledge of timber as a material and its various uses in construction and furniture making.

Lesson Content/Board Summary

Methods of Seasoning Timber

Definition of Timber Seasoning

Timber seasoning is the process of reducing the moisture content in freshly cut timber to an acceptable level suitable for its intended use. This process prevents defects like warping, splitting, and fungal decay, making the timber more stable and durable.

Methods of Seasoning Timber

There are two main methods of seasoning timber:

Air Seasoning (Natural Seasoning)
Kiln Seasoning (Artificial Seasoning)

Air Seasoning

Air seasoning is the natural process of drying timber by exposing it to the open air. This method relies on natural air circulation to gradually remove moisture from the wood.

The process of air seasoning involves:

Timber is stacked in a way that allows air to circulate freely around each piece.
Stickers (small pieces of wood) are placed between layers of timber to create air gaps.
The stacks are usually covered at the top to protect them from direct rain and sun.
The drying process is slow and can take several months to years depending on the timber type and thickness.

The advantages of air seasoning are:

It is inexpensive.
It requires less skilled labour.
It produces timber with good strength properties.

The disadvantages of air seasoning are:

It is a very slow process.
It requires a large area for stacking.
The final moisture content cannot be precisely controlled.
Timber can be susceptible to fungal attack and insect infestation during drying.

Kiln Seasoning

Kiln seasoning is an artificial method of drying timber in a controlled environment called a kiln. This method uses heat and controlled humidity to speed up the drying process.

The process of kiln seasoning involves:

Timber is loaded into a sealed chamber (kiln).
Heat is introduced, usually through steam pipes, to raise the temperature inside the kiln.
Humidity levels are controlled by introducing steam or venting moist air.
Fans are used to circulate the hot, moist air around the timber.
The drying schedule is carefully controlled to prevent defects and achieve a specific moisture content.

The advantages of kiln seasoning are:

It is a much faster process than air seasoning.
The final moisture content can be accurately controlled.
It kills insects and fungi present in the timber.
It requires less space compared to air seasoning.

The disadvantages of kiln seasoning are:

It is expensive to set up and operate.
It requires skilled operators.
Improper control can lead to drying defects like case hardening and collapse.

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 what happens to fresh wood when left to dry naturally. The teacher then introduces the topic: Methods of Seasoning Timber.
Pupils’ Activity: Pupils respond to the teacher’s questions and listen attentively to the introduction.
Learning Point: Pupils are prepared for the lesson and recall prior knowledge about timber.

Step 2: Definition of Timber Seasoning

Time: 5 minutes
Teaching Skill: Explanation
Teacher’s Activity: The teacher defines timber seasoning, explaining its purpose and importance in furniture making and construction. The teacher writes the definition on the board.
Pupils’ Activity: Pupils listen, take notes, and ask questions for clarification.
Learning Point: Pupils understand the meaning and importance of timber seasoning.

Step 3: Explanation of Air Seasoning

Time: 10 minutes
Teaching Skill: Demonstration/Explanation
Teacher’s Activity: The teacher explains air seasoning as a natural method. Using charts, the teacher demonstrates how timber is stacked for air seasoning, emphasizing the use of stickers and protective covers. The teacher highlights the process and principles involved.
Pupils’ Activity: Pupils observe the charts, listen to the explanation, and ask questions about the stacking method.
Learning Point: Pupils understand the process and setup for air seasoning.

Step 4: Advantages and Disadvantages of Air Seasoning

Time: 5 minutes
Teaching Skill: Listing/Discussion
Teacher’s Activity: The teacher lists and explains the advantages and disadvantages of air seasoning, encouraging pupils to discuss practical implications.
Pupils’ Activity: Pupils listen, note the points, and contribute to the discussion.
Learning Point: Pupils identify the pros and cons of air seasoning.

Step 5: Explanation of Kiln Seasoning

Time: 10 minutes
Teaching Skill: Demonstration/Explanation
Teacher’s Activity: The teacher explains kiln seasoning as an artificial method. Using charts, the teacher shows a diagram of a kiln dryer and explains how heat, humidity, and air circulation are controlled to dry timber quickly.
Pupils’ Activity: Pupils observe the charts, listen carefully, and compare it with air seasoning.
Learning Point: Pupils understand the process and principles of kiln seasoning.

Step 6: Advantages and Disadvantages of Kiln Seasoning

Time: 5 minutes
Teaching Skill: Listing/Discussion
Teacher’s Activity: The teacher lists and explains the advantages and disadvantages of kiln seasoning, relating them to cost and quality control.
Pupils’ Activity: Pupils listen, note the points, and participate in the discussion.
Learning Point: Pupils identify the pros and cons of kiln seasoning.

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 timber seasoning.
Mention two methods of seasoning timber.
State two advantages of air seasoning.
Explain one disadvantage of kiln seasoning.

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
Teacher’s Activity: The teacher summarizes the main points of the lesson, reiterating the importance of seasoning timber. The teacher gives homework: “Draw a simple diagram showing timber stacked for air seasoning.”
Pupils’ Activity: Pupils listen to the summary and copy down the homework assignment.
Learning Point: Pupils consolidate their learning and prepare for further study.

Lesson Keywords

Seasoning – The process of reducing moisture content in timber.
Air Seasoning – Natural drying of timber by exposure to air.
Kiln Seasoning – Artificial drying of timber in a controlled heated chamber.
Moisture Content – The amount of water present in timber, expressed as a percentage of its dry weight.
Stickers – Small pieces of wood used to separate layers of timber in a stack for air circulation.

Differentiation

For pupils who grasp concepts quickly, the teacher can ask them to research other lesser-known methods of seasoning or the specific moisture content requirements for different timber uses. For pupils who require more support, the teacher will provide simplified diagrams and allow more time for practical observation and questioning.

Note for teachers using this lesson plan

Teachers should ensure that actual timber samples (both unseasoned and seasoned) are brought to class for pupils to feel and observe the difference. Emphasize safety precautions if demonstrating any aspect of timber handling. Encourage pupils to relate the lesson to local carpentry practices.