Class: Senior Secondary School 1 (SS1, SS 1, SSS1, SSS 1)
Term: 1st Term
Week: 7
Age: 15 years
Duration: 45 minutes
Subject: Wood Work
Curriculum Theme: Vocational Studies
Previous Lesson: Timber Conversion Methods.
Topic: TIMBER CONVERSION CHARACTERISTICS AND MARKET SIZES
Subject Matter: characteristics of sawing methods, common timber market sizes, timber dimensions

Specific Objectives

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

Cognitive Domain:

Define timber conversion.
List two methods of timber conversion.
State two characteristics of plain sawing and quarter sawing.
Identify common timber market sizes.

Affective Domain:

Appreciate the importance of proper timber conversion techniques.
Show interest in selecting appropriate timber sizes for different projects.

Psychomotor Domain:

Sketch common timber market sizes.
Identify different timber dimensions from samples or charts.

Collaborate with peers to identify different timber characteristics.

Reference Materials

The following resources were used in planning this lesson:

9 Years Basic Education Curriculum for Basic Technology (JSS).
State Unified Scheme of Work for Senior Secondary Schools.
Wood Work for Senior Secondary Schools by A.O. Okoro.

Instructional Materials

The teacher will teach this lesson with the aid of:

Posters and charts illustrating timber conversion methods.
Actual timber samples of different market sizes (e.g., 2×2, 2×4, 1×12).
Measuring tape.
Whiteboard/chalkboard and markers/chalk.

Rationale for the Lesson

This lesson helps pupils understand how timber logs are processed into usable forms and the standard sizes available in the market. This knowledge is important for selecting the correct timber for various woodworking projects and ensuring efficient use of resources in daily life.

Prerequisite/Previous Knowledge

Pupils are expected to have basic knowledge of timber as a material and its various sources from previous lessons.

Lesson Content/Board Summary

TIMBER CONVERSION CHARACTERISTICS AND MARKET SIZES

1. Timber Conversion Methods

Timber conversion is the process of sawing logs into usable forms such as planks, boards, scantlings, and other sections suitable for construction and furniture making.

Common timber conversion methods include:

Plain sawing (through and through sawing)
Quarter sawing
Tangential sawing

2. Characteristics of Sawing Methods

Each sawing method produces timber with distinct characteristics affecting its grain pattern, stability, and yield.

a. Plain Sawing (Through and Through Sawing):

It is the most economical method as it involves minimal turning of the log.
Produces wider boards.
Grain patterns are varied, often featuring cathedral patterns.
Timber is more prone to warping, twisting, and shrinking due to tangential shrinkage.

b. Quarter Sawing:

Produces timber with greater dimensional stability.
Exhibits attractive straight grain patterns and prominent medullary rays (figure).
Higher wastage compared to plain sawing, making it more expensive.
More resistant to warping, twisting, and shrinking.

3. Common Timber Market Sizes and Dimensions

Timber is typically sold in standard market sizes, specified by its thickness, width, and length. These dimensions are important for planning and executing woodworking projects.

Common timber dimensions in the Nigerian market (often given in inches or millimetres) include:

2″ x 2″ (50mm x 50mm)
2″ x 3″ (50mm x 75mm)
2″ x 4″ (50mm x 100mm)
2″ x 6″ (50mm x 150mm)
1″ x 12″ (25mm x 300mm)
1″ x 6″ (25mm x 150mm)

Length is commonly measured in feet (e.g., 12ft, 14ft, 16ft) or metres.

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 on sources of timber, and then introduces the new topic by asking pupils how they think large tree trunks are turned into planks and boards.
Pupils’ Activity: Pupils respond to questions and listen attentively.
Learning Point: Pupils are prepared for the new lesson and link it to prior knowledge.

Step 2: Explanation of Timber Conversion Methods

Time: 10 minutes
Teaching Skill: Explanation/Demonstration
Teacher’s Activity: The teacher defines timber conversion and explains different methods like plain sawing and quarter sawing, using charts and posters to illustrate the process.
Pupils’ Activity: Pupils observe the charts, listen to the explanations, and ask questions for clarification.
Learning Point: Pupils understand what timber conversion is and the main methods used.

Step 3: Discussion of Characteristics of Sawing Methods

Time: 10 minutes
Teaching Skill: Elaboration/Discussion
Teacher’s Activity: The teacher further explains the characteristics of plain sawing and quarter sawing, highlighting the advantages and disadvantages of each in terms of yield, stability, and appearance. The teacher uses diagrams to show grain patterns.
Pupils’ Activity: Pupils participate in the discussion, comparing the characteristics of each method.
Learning Point: Pupils understand how different sawing methods affect the final timber product.

Step 4: Introduction to Common Timber Market Sizes

Time: 5 minutes
Teaching Skill: Presentation/Demonstration
Teacher’s Activity: The teacher presents various actual timber samples of common market sizes (e.g., 2×2, 2×4, 1×12) or uses charts showing these sizes. The teacher names and describes them.
Pupils’ Activity: Pupils observe the timber samples/charts and listen to the names and descriptions of different sizes.
Learning Point: Pupils become familiar with standard timber market sizes.

Step 5: Explanation of Timber Dimensions

Time: 5 minutes
Teaching Skill: Explanation/Practical Application
Teacher’s Activity: The teacher explains what timber dimensions refer to (thickness, width, and length). The teacher demonstrates how to measure these dimensions using a measuring tape on the timber samples.
Pupils’ Activity: Pupils pay attention to the explanation and demonstration, understanding how timber is dimensioned.
Learning Point: Pupils understand how timber dimensions are specified and measured.

Step 6: Practical Identification and Sketching

Time: 5 minutes
Teaching Skill: Practical Application
Teacher’s Activity: The teacher guides pupils to identify different timber sizes from the samples and encourages them to sketch simple representations of these sizes in their notebooks.
Pupils’ Activity: Pupils actively identify samples and attempt to sketch them, reinforcing their understanding of different dimensions.
Learning Point: Pupils apply their knowledge to practically identify and represent timber sizes.

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 conversion.
Mention two common methods of timber conversion.
State two characteristics of plain sawing.
List three common timber market sizes.

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 understanding timber conversion and market sizes for practical woodworking. The teacher gives homework: “Draw and label three common timber market sizes.”
Pupils’ Activity: Pupils listen to the summary and copy the homework.
Learning Point: Pupils consolidate their learning and prepare for independent practice.

Lesson Keywords

Timber conversion – The process of sawing logs into usable forms like planks and boards.
Plain sawing – A timber conversion method where logs are sawn through and through, resulting in wide boards but less stability.
Quarter sawing – A timber conversion method where logs are first quartered before sawing, producing more stable timber with attractive grain patterns.
Market sizes – Standard dimensions in which timber is sold in the market.
Dimensions – The measurements of timber, typically thickness, width, and length.

Differentiation

For struggling learners, the teacher will provide more one-on-one guidance during the practical identification and sketching activities and use simplified diagrams. Advanced learners will be challenged to research the specific uses of different timber sizes and the reasons for choosing certain conversion methods for particular applications.

Note for teachers using this lesson plan

Ensure that actual timber samples or clear, large-scale charts are available for pupils to observe and interact with. Encourage pupils to use measuring tapes to understand dimensions practically. Emphasize safety precautions if using any tools for demonstration.