Processing of Materials – Wood (contd.)

Subject   :  Civic Education

Class  : Basic 9 / JSS 3

Term : First Term  (1st Term)

Week  : Week 3

Topic  :

Processing of Materials – Wood (contd.)

Previous Knowledge : The pupils have previous knowledge of.

Career Prospects and Opportunities in Technology

that was taught  in their previous classes

Behavioural  Objectives : At the end of the lesson , pupils should be able to

• Explain the meaning of wood
• Say the uses of wood
• Mention the materials that are used for processing wood

Instructional Materials 

• Wall charts
• Pictures
• Online Resource
• Textbooks

Methods of Teaching 

• Role modelling
• Questions and Answers
• Explanation
• Discussion
• Recitation
• Imitation

Content :  

Conversion

Wood is obtained from trees that grow all around us. However, wood cannot be used to produce the materials needed domestically and industrially, if the wood does not pass through the necessary stages of being processed.

Wood conversion is the process of splitting the log at sawmill with sawing machines into commercial and/or marketable sizes. The two popular methods of conversion are: ‘plain sawn’ and ‘quarter sawn’.

In the plain sawn method also commonly called flat sawn, is the most common type of lumber cut you will find. Many operators prefer this method because it is a simple, cheap and fast way to convert logs into planks suited to various needs. The annular rings are generally 30 degrees or less to the face of the board; this is often referred to as tangential grain. The log is converted into planks by cutting more attention than the plain sawn method because the log has to be turned. The planks produced by this method have stripe figures.

Quarter sawn is more expensive than plain sawn timber, it has an amazing straight pattern that lends itself to design. Quarter sawn lumber is defined as wood where the annular growth rings intersect the face of the board at a 60 to 90 degree angle. When cutting this lumber at sawmill, each log is sawed at a radial angle into four quarters, hence the name.

Quarter-sawn boards have greater stability of form and size with less cupping, shrinkage across the width, shake and splitting, and other good qualities. In some woods, such as oak, the grain produces a decorative effect which shows a prominent ray fleck and sapele is likely to produce a ribbon figure.

Seasoning

Freshly cut wood contains a lot of water or moisture, which makes it heavy. Seasoning is the process of reducing the water (moisture) in the wood. The reasons for seasoning or drying wood are:

1. It makes wood more stable
2. It makes wood lighter in weight and therefore easier to transport
3. It generally makes wood stronger
4. It makes wood more durable because insects and fungi usually attack the starch in the wet sapwood.
5. It makes wood absorb paints, polishes, etc., more easily
6. It makes wood absorb preservatives more easily
7. Wood may be seasoned either by air drying or kiln drying. Air drying involves stacking planks one on top of the other with pieces of wood called stackers used to separate them. The stack can either be in open air or under a roof. Air drying takes a few days, this is because in kiln drying, the stack of timber is placed in a specially heated chamber. The air is therefore hotter and dries the timber faster.

Presentation  

The topic is presented step by step

Step 1 : The class teacher revises the old topic

Step 2 : The class teacher introduces the new topic

Step 3 : The class teacher allows the pupils to give their own contributions and gives room for pupils” participation

Class Teacher And Pupils Activities. Interaction or  Participation 

This involves class teacher  and pupils interaction , conversation , imitation or modeling through discussion , play method or just by recitation or asking and answering questions that are related to the topic that has just been taught

• The class teacher will show the learners some wood
• Students are made to mention some types of wood processing methods

Evaluation  :State five reasons for seasoning wood

1. ____________

2. ____________

3. ____________

4. ____________

5. ____________

Conclusion 

The class teacher does the necessary corrections and he or she goes round to mark

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