Lesson Notes By Weeks and Term v4 - JHS 1

Lesson Video

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Performance objectives

• Explain what resistant materials are
• Describe how wood and metals are obtained
• Distinguish between solid timber and man-made boards
• Identify various materials used in construction
• Discuss the sources of natural building materials in Ghana

Lesson summary

Welcome, learners! Look around our classroom. The desk you are sitting at, the windows, the roofing sheets on our school building, and even the nails holding things together are all made from special materials. These are called Resistant Materials because they are tough, strong, and can resist forces like scratching, bending, and breaking. They are the backbone of construction, manufacturing, and technology. Understanding where they come from helps us appreciate their value, use them wisely, and think about their impact on our environment in Ghana.

Lesson notes

What are Resistant Materials? Resistant materials are materials that can withstand forces and wear without easily breaking or changing shape. They are used to make strong and durable products. The main categories we will study are Wood, Metals, and Building Materials.

Part 1: WOOD A. How Wood (Timber) is Obtained Getting usable wood from a living tree is a multi-step process. Imagine we want to get planks from a large Odum tree in a forest. Here are the steps: Felling: This is the first step where a mature, selected tree is carefully cut down using tools like a chainsaw or an axe. De-branching / Logging: Once the tree is on the ground, all the branches are cut off. The main, thick stem that is left is called a log. Conversion (Sawing): The log is transported to a sawmill. Here, large machines saw the log into usable standard sizes of timber, such as planks, beams, and boards. This process is called conversion. Seasoning: Freshly cut wood contains a lot of water (moisture or sap), which makes it weak and likely to warp or shrink. Seasoning is the process of drying the wood to remove this excess moisture. This can be done naturally (stacking the wood in the open air) or artificially (using a large oven called a kiln). Seasoned wood is stronger, lighter, and more stable.

Summary of Process: `Tree` → Felling → `Fallen Tree` → De-branching → `Log` → Conversion → `Planks/Boards` → Seasoning → `Usable Timber` B. Solid Timber vs. Man-made Boards We can group wood products into two main types: Solid Timber: This is natural wood cut directly from a log. It is the wood in its most natural form. Examples in Ghana: Odum, Wawa, Mahogany, Teak, Emire. Man-made Boards (Manufactured Boards): These are boards made by humans, usually by gluing together small pieces of wood, wood fibres, or wood waste under heat and pressure. Examples in Ghana: Plywood, Blockboard, Particleboard (Chipboard), MDF (Medium-Density Fibreboard).

Comparison Table:

Evaluation guide

• B7.2.2.1
• Demonstrate knowledge of
• basic concept of resistant
• materials