Class: Senior Secondary School 1 (SS1 / SSS1)
Term: 1st Term
Week: 10
Age: 15 years
Duration: 45 minutes
Subject: Machine Wood Work
Curriculum Theme: Technology
Previous Lesson: Timber Conversion: Definition, Methods And Market Sizes.
Topic: Timber Conversion
Subject Matter: Through and through sawing, Tangential sawing, Rift and quarter sawing, Market timber sizes
Specific Objectives
By the end of the lesson, pupils should be able to:
Cognitive Domain:
- Define timber conversion.
- State the different methods of timber conversion.
- Identify common market timber sizes.
Affective Domain:
- Appreciate the importance of proper timber conversion for efficient wood use.
- Show interest in learning about various sawing methods.
Psychomotor Domain:
- Sketch simple diagrams illustrating each sawing method.
- List at least five common market timber sizes.
Social Domain:
- Participate actively in class discussions about timber conversion.
- Work cooperatively with peers to discuss timber uses.
Reference Materials
The following resources were used in planning this lesson:
- 9 Years Basic Education Curriculum for Technology.
- State Unified Scheme of Work for Machine Wood Work (SSS1).
- Akinwande, O. (2018). Basic Technology for Senior Secondary Schools 1. Ibadan: University Press PLC.
- https://nigeriancurriculum.com/basic-technology-sss1-curriculum
- https://www.waeconline.org.ng/e-learning/Tech/Woodwork/Woodwork_SS1_SS2_SS3.pdf
Instructional Materials
The teacher will teach this lesson with the aid of:
- Diagrams or charts showing different sawing methods.
- Samples of timber sections (if available).
- Saw blades (actual or pictorial representations).
- Whiteboard and markers.
Rationale for the Lesson
This lesson helps pupils understand how logs are cut into usable timber. Knowing the different sawing methods and market sizes enables them to select appropriate timber for various construction and woodworking projects, promoting efficient use of wood resources.
Prerequisite/Previous Knowledge
Pupils should have basic knowledge of trees, wood as a material, and simple hand tools used in woodworking.
Lesson Content/Board Summary
Timber Conversion
Definition of Timber Conversion
Timber conversion is the process of cutting logs into usable sizes and shapes of timber for various purposes. This process involves different sawing methods that determine the grain pattern and stability of the resulting wood.
Methods of Timber Conversion (Sawing Methods)
The following are common methods used for timber conversion:
- Through and Through Sawing
- Tangential Sawing (Slab Sawing or Flat Sawing)
- Rift and Quarter Sawing
Through and Through Sawing
This is the simplest and most common method of sawing. The log is sawn into parallel boards without turning it. Cuts are made across the entire width of the log, producing boards with mixed grain patterns.
Advantages:
- Simple and fast.
- Produces maximum yield of timber.
- Economical due to less waste.
Disadvantages:
- Boards are prone to warping and twisting.
- Produces uneven grain patterns.
- Less stable timber.
Tangential Sawing (Slab Sawing or Flat Sawing)
In this method, the log is cut tangentially to the annual rings. This produces boards with distinctive “cathedral” patterns on the face and often wider boards. The log is usually turned after each cut to maintain the tangential cut.
Advantages:
- Produces attractive grain patterns.
- Yields wider boards.
- Commonly used for decorative timber.
Disadvantages:
- Boards are more prone to cupping and checking.
- Less stable than quarter-sawn timber.
- More waste than through and through sawing.
Rift and Quarter Sawing
This method involves cutting the log radially, perpendicular to the annual growth rings. The log is first cut into quarters, and then each quarter is sawn. This produces boards with vertical or nearly vertical grain patterns.
Advantages:
- Produces highly stable timber.
- Less prone to warping, twisting, and cupping.
- Shows attractive straight grain patterns.
- Good for flooring and furniture.
Disadvantages:
- More complex and time-consuming.
- Produces more waste.
- More expensive due to lower yield and processing time.
Market Timber Sizes
Market timber sizes refer to the standard dimensions in which timber is sold in the market. These sizes are typically expressed in inches (length x width x thickness) or in feet for length.
The following are examples of common market timber sizes:
- 1″ x 12″ (one by twelve)
- 2″ x 2″ (two by two)
- 2″ x 4″ (two by four)
- 2″ x 6″ (two by six)
- 2″ x 12″ (two by twelve)
- 3″ x 3″ (three by three)
- 4″ x 4″ (four by four)
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 reviews the previous lesson briefly. The teacher then introduces the topic “Timber Conversion” by asking pupils how logs are turned into planks and boards they see. The teacher states the lesson objectives.
Pupils’ Activity: Pupils respond to questions and listen attentively.
Learning Point: Pupils are prepared for the lesson and aware of the topic and objectives.
Step 2: Definition of Timber Conversion
Time: 7 minutes
Teaching Skill: Explanation/Definition
Teacher’s Activity: The teacher defines timber conversion as the process of cutting logs into usable sizes and shapes. The teacher explains that different methods are used depending on the desired outcome of the timber.
Pupils’ Activity: Pupils listen, take notes, and ask questions for clarification.
Learning Point: Pupils understand what timber conversion means.
Step 3: Explanation of Through and Through Sawing
Time: 8 minutes
Teaching Skill: Illustration/Description
Teacher’s Activity: The teacher explains “Through and Through Sawing,” describing how the log is sawn into parallel boards without turning. The teacher uses diagrams or sketches on the board to illustrate this method and discusses its advantages and disadvantages.
Pupils’ Activity: Pupils observe the diagrams, listen, take notes, and sketch the method.
Learning Point: Pupils understand the process, advantages, and disadvantages of through and through sawing.
Step 4: Explanation of Tangential Sawing
Time: 8 minutes
Teaching Skill: Illustration/Description
Teacher’s Activity: The teacher explains “Tangential Sawing,” detailing how cuts are made tangentially to the annual rings. The teacher uses diagrams to show the cutting pattern and discusses the characteristics (e.g., grain pattern) and disadvantages of timber produced by this method.
Pupils’ Activity: Pupils observe diagrams, listen, take notes, and sketch the method.
Learning Point: Pupils understand the process, advantages, and disadvantages of tangential sawing.
Step 5: Explanation of Rift and Quarter Sawing
Time: 8 minutes
Teaching Skill: Illustration/Description
Teacher’s Activity: The teacher explains “Rift and Quarter Sawing,” describing it as cutting the log radially. The teacher uses diagrams to illustrate the complex cutting pattern and highlights the stability and straight grain produced, along with its disadvantages.
Pupils’ Activity: Pupils observe diagrams, listen, take notes, and sketch the method.
Learning Point: Pupils understand the process, advantages, and disadvantages of rift and quarter sawing.
Step 6: Discussion of Market Timber Sizes
Time: 4 minutes
Teaching Skill: Listing/Identification
Teacher’s Activity: The teacher explains that timber is sold in standard dimensions called market timber sizes. The teacher lists and writes common examples of market timber sizes on the board (e.g., 2×2, 2×4, 1×12).
Pupils’ Activity: Pupils listen, take notes, and identify the listed sizes.
Learning Point: Pupils can identify common market 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 methods of timber conversion.
- State one advantage of through and through sawing.
- List three common market timber 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/Assignment
Teacher’s Activity: The teacher summarizes the key points of the lesson, emphasizing the importance of choosing the correct sawing method for specific applications. The teacher assigns homework: “Sketch and label the three methods of timber conversion discussed in class.”
Pupils’ Activity: Pupils listen to the summary and copy the homework.
Learning Point: Pupils consolidate their learning and have a task to reinforce understanding.
Lesson Keywords
- Timber Conversion – The process of cutting logs into usable sizes and shapes of timber.
- Through and Through Sawing – A method where logs are sawn into parallel boards without turning.
- Tangential Sawing – A method where logs are cut tangentially to the annual rings, producing wide boards with distinctive grain patterns.
- Rift and Quarter Sawing – A method where logs are cut radially, perpendicular to the annual rings, producing stable timber with straight grain.
- Market Timber Sizes – Standard dimensions in which timber is sold in the market.
Differentiation
For pupils who grasp concepts quickly, the teacher can ask them to research other less common timber conversion methods. For pupils who need more support, the teacher will provide additional one-on-one guidance and simplified diagrams, focusing on the basic definitions and identification of methods.
Note for teachers using this lesson plan
Teachers should ensure they have clear, visible diagrams or actual timber samples to effectively demonstrate the different sawing methods. Encourage pupils to actively participate in sketching to reinforce their understanding of the cutting patterns.
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