Properties of Materials – Wood

Subject : BASIC TECHNOLOGY

 

Term : FIRST TERM

 

Week: Week 5

 

Class : JSS1

 

 

Previous lesson : 

The pupils have previous knowledge of   SAFETY GUIDELINES- ROAD SIGNS

 

Topic :

MATERIALS AND PROCESSING – IDENTIFICATION OF WOOD

Behavioural objectives :

At the end of the lesson,  pupils should be able to say the

  • different types of wood that we have
  • properties of wood
  • beneficial uses of woods in construction , domestic use and use of furniture
  • major internal and external parts of wood

Instructional Materials :

  • Wall charts
  • Pictures
  • Related Online Video
  • Flash Cards

Methods of Teaching :

  • Class Discussion
  • Group Discussion
  • Asking Questions
  • Explanation
  • Role Modelling
  • Role Delegation

 

Reference Materials :

  • Scheme of Work
  • Online Information
  • Textbooks
  • Workbooks
  • 9 Year Basic Education Curriculum
  • Workbooks

MATERIALS AND PROCESSING-IDENTIFICATION OF WOOD

CONTENT

  1. Identification of Wood
  2. The Structure of Wood (internal)
  3. Major Parts of a Tree (external)
  4. Types of Wood
  5. Uses of Wood

IDENTIFICATION OF WOOD

The materials used in technology include woods, metals, ceramics, rubbers and plastics. These materials come in different forms and each form performs a unique function. Wood is a hard fibrous substance that chiefly composes trees and bushes and is found beneath their bark.

Wood is one of the materials used in furniture making and in building construction. Different types of wood are identified by:

  • their color,
  • classification into soft and hard woods
  • their properties e.g. hardwood has broad leaves while soft wood has needle – like leaves.

THE INTERANAL STRUCTURE OF A WOOD

 

The internal structure of wood is made up of the following:

  1. Pith
  2. Xylem
  3. Phloem
  4. Cambium
  5. Cork cambium
  6. Bark

There are trees all around us. Some are big and some are small.

MAJOR PARTS OF A TREE (EXTERNAL)

The major parts of a tree are:

  1. roots
  2. trunks (branches)
  3. leaves
  4. flowers and
  5. seeds

When a tree is allowed to remain for a long time, its trunk (stem) becomes bigger and bigger and the tree grow taller. The tree trunks are cut into wood or timber.

 

Properties of Materials and Identification of wood, timber, structure of wood

Felling of trees can be done in two places: Free Areas and Forest Reserve.

Free area is one that is owned by individual. Trees can be cut down thereafter consulting the owner, but the contractor will pay certain amount of money through forest guard to the government, this is called ‘Tariff’.

A forest reserve is a very large area of land owned by the government. The wood can only be cut down there when getting approval from the government.

The company usually bought tree from forest reserve. The timber contractor pays for the total volume of timber taken out. The money paid is known as O.T.V i.e. Out Turn Volume.

The Growth of Timber and Wood Structure

The tree need food to grow, this food is absorbed by the roots in the soil. It passes through the sapwood to the leaves where chemical reaction takes place through the sunlight. The food will now be transferred to the tree through the blast.

 

CLASSES OF WOOD

We have two classes of wood namely:

  1. HARD WOOD
  2. SOFT WOOD

PROPERTIES OF HARD WOOD

  1. It is dark in colour.
  2. They are gotten from DECIDUOUS TREES.
  3. It has a complex cellular structure
  4. It is heavy.
  5. It has annual rings which are not visible.
  6. Hardwood trees have broad leaves.
  7. Examples include Iroko ,Afara , Mahogany ,Opepe, Omo e.t.c.

Hard wood is used for furniture making and building construction.

PROPERTIES OF SOFT WOOD

  1. It has lighter colour than hardwood.
  2. It is not heavy.
  3. It is easy to work on.
  4. It is gotten from CONIFEROUS TREE.
  5. Softwood trees have narrow and needle like leaves.
  6. Softwood trees are usually evergreen because they do not shed their leaves in dry season.
  7. Examples include spruce, fine, cedar, cypress e.t.c
  8. These are trees that bear naked seeds called (cones)
  9. These trees grow better in a temperate region (cold region of the world)

USES OF WOOD

Wood is used today in the following industries and processes:

  1. HOUSING: Wood is used for home furniture as doors, window and roofing.
  2. INDUSTRIAL BUILDING: Many industries are constructed using wood.
  3. JOINERY: Wood is used for making staircase in our buildings today.
  4. PACKAGING: Packaging technologist cannot do without wood for making crates, pallet, and packaging electronics equipment.
  5. FURNITURE; Chairs, bed, wardrobes, table book-cases etc.
  6. TRANSPORT: Railway, train-wagons, lorry-body.
  7. BRIDGES AND POLES: Most farm bridges and bridges across the roads in villages are made with wood. Some electric poles and railway sleepers are made of wood.
  8. PULP AND PAPER: Exercise book, textbooks, magazines e.t.c are made from pulp and paper derived from wood.
  9. MEDICINE: People who have their arms and legs amputated (cut off) such are usually replaced by artificial limbs made from wood.
  10. CLOTHING: Most heels and some soles shoes are made from wood e.g. the rayon stocking.
  11. TOOL MAKING: Handles for hammer, pick axes, felling axes, screw driver and many other tools are made from wood.

 

Five main parts cross section, classes and properties.

The five main parts of tree are:

  1. Root: It searches for various mineral salts in the moist ground. They also hold the tree firmly in the ground.
  2. Trunk or Stem: is part that acts as a support for the branches which rises as high as possible towards the light. It is from the trunk that we get our timber.
  3. Branches: develop at leaves.
  4. Leaves: These manufacture food for the tree through the action of sunlight and air.
  5. Bark: protects the growing part of the tree from the weather, animals and any other injuries.

The features of the cross-section of a tree when felled are:

  1. The Cambium Layer is actual living part.
  2. Sapwood is active part of tree.
  3. Heartwood is the mature part of the tree.
  4. Pith: The Central core of the trunk
  5. Medullar Rays are food storage cells.

The Structure of Wood

Wood is made up of a number of tiny tube- like units called ‘cells’. These cells are called fibres or tracheids. Wood is composed of cellulose (60%) lignin (28%) and other minor materials.

Wood can be classified into two namely:

  1. Hardwood or Deciduous trees
  2. Softwood or Coniferous trees or simply conifers

Hardwood or Deciduous Tree: These trees have broad leaves. (a) Their seeds are enclosed in cases. (b) The trees shed their leaves at least every year (c) It produce the timbers used for our furniture and in construction (d) It grows in the temperate and tropical regions of the world. Examples of Nigerian broad leaved trees are: Iroko, Afara, Mahogany, Opepe, Omo etc.

Softwood or Coniferous Trees or Simply Conifers

These trees have needle-like leaves

 

(a) They bear naked seeds which are in cones that are why it is referred to as conifers.

(b) They do not shed their leaves.

(c) They are said to be evergreen because their branches always bear green leaves.

(d) It produces the commercial softwoods

 

Presentation

 

The topic is presented step by step

 

Step 1:

The class teacher revises the previous topics

 

Step 2.

He introduces the new topic

 

Step 3:

The class teacher allows the pupils to give their own examples and he corrects them when the needs arise

 

 

Conclusion

The lesson is concluded when the class teacher wraps up the lesson by giving the pupils some notes.

The class teacher also goes round to make sure that the notes are well copied or well written by the pupils.

He or she does the necessary corrections when and where  the needs arise.

 

EVALUATION

 

  1. How many classes of wood do we have?
  2. Name three examples of Hardwood tree.
  3. Mention two features of Softwood.
  4. State two differences between softwood and hardwood.
  5. Draw and name five main parts of tree.
  6. Differentiate between hard and soft wood.
  7. Mention five (5) uses of wood.

 

WEEKEND ASSIGNMENT

  1. ____ is a hard fibrous substance that chiefly composes trees and bushes and is found beneath their bark (a) Tree (b) Plastics (C) Metal (d) Wood
  2. The materials used in technology include the following except (a) wood (b) metals

(c) ceramics (d) cassava

3.The major parts of a tree are as follow except (a) roots (b) trunks (branches) and leaves (c) flowers and seeds (d) furniture

4.____ are trees that shed their leaves in the dry season to prevent water loss. e.g. Iroko, Afara, Mahogany, Opepe, Omo (a) Hard wood trees (b) Soft wood trees (c) Di-cotyledonous trees (d) Coniferous trees

5.Examples of soft wood trees include the following except (a) spruce and vine (b) cedar

(c) cypress (d) Afara

THEORY

  1. Explain why wood is referred to as a material for technology.
  2. Draw the major parts of a tree (external).
  3. State and give examples of the types of wood.
  4. Draw the structure of wood (internal).
  5. How many classes of wood do we have? (a) 6 (b) 4 (c) 2 (d) 10
  6. ______ can also be called deciduous tree. (a) pawpaw tree (b) hardwood (c) softwood (d) water leaf
  7. The central core of the truck is called _____ (a) medullar raw (b) pith (c) sapwood (d) heartwood
  8. The money to be paid in Free Area is called ______ (a) O.T.V (b) coins (c) Tariff (d) naira
  9. _________ protects the growing part of the tree from the weather, animal and other injuries. (a) Root (b) trunk (c) leaves (d) bark.
  10. Mention the materials used in technology.

 

 

Assignment

Prepare for the next lesson by reading about Properties of materials  – Metals

 

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