Lesson Notes By Weeks and Term v5 - Grade 7

Lesson Video

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Performance objectives

• Identify and classify common materials.
• Describe the function and safe use of five basic hand tools.
• Explain basic processing techniques for different materials.
• Design and sketch a simple product.
• Demonstrate safe working practices.

Lesson summary

This week, we delve into the exciting world of processing basic materials using various tools. Processing refers to the activities that change the shape, size, or properties of a material. Understanding processing techniques and the tools involved is crucial because it allows us to create useful products and solve everyday problems. In South Africa, a strong understanding of these principles is vital for small businesses, artisans, and larger industries involved in manufacturing, construction, and agriculture. Imagine needing to fix a broken fence post on your farm – knowing the right tool and processing method can save you time and money!

Lesson notes

What is Processing? Processing involves transforming raw materials into usable products. This transformation can involve changing the shape, size, surface finish, or other properties of the material. Think about turning a log of wood into a chair, a sheet of metal into a car panel, or fabric into clothing. All of these require processing.

Basic Materials: Wood: A natural material obtained from trees. It is strong, relatively easy to work with, and readily available in many parts of South Africa. Different types of wood have different properties. Pine, for example, is softer than hardwood like mahogany. Wood is often used in construction, furniture making, and crafting.

Metal: Metals are strong, durable, and often conductive (they can carry electricity). Common metals include steel, aluminum, copper, and iron. Metal is used in everything from building bridges to making cooking pots. Different metals have different strengths, weaknesses and uses.

Plastic: A synthetic material made from polymers. Plastics are versatile, lightweight, and can be molded into various shapes. They are used in packaging, toys, furniture, and many other products. Different types of plastics include polyethylene (PE), polypropylene (PP) and polyvinyl chloride (PVC).

Fabric: A flexible material made from fibers. Fabrics can be natural (like cotton or wool) or synthetic (like polyester or nylon). They are used for clothing, upholstery, and other textile applications.

Properties of Materials: Understanding the properties of materials is crucial for choosing the right material and processing technique.

Key properties include: Strength: The ability to withstand force without breaking.

Hardness: The resistance to scratching or indentation.

Flexibility: The ability to bend without breaking.

Durability: The ability to withstand wear and tear.

Workability: How easy it is to shape or process the material.

Basic Tools and Their Uses: Saw: Used for cutting materials, especially wood. Different types of saws (e.g., handsaw, jigsaw, hacksaw) are used for different tasks.

Handsaw:* A general-purpose saw for cutting wood.

Hacksaw:* Used for cutting metal and plastic.

Jigsaw:* Used for cutting curves and intricate shapes in wood, metal, or plastic.

Safe Use: Always hold the material securely, keep your fingers away from the blade, and cut in a smooth, controlled motion. Wear safety glasses to protect your eyes from flying debris.

Hammer: Used for driving nails or shaping metal.

Claw Hammer:* Used for driving nails into wood and removing them.

Ball-peen Hammer:* Used for shaping metal.

Safe Use: Keep your eye on the nail head, hold the hammer firmly, and strike with a controlled swing.

File: Used for smoothing rough edges and shaping metal or wood.

Flat File:* General-purpose file for smoothing flat surfaces.

Round File:* Used for smoothing curved surfaces and enlarging holes.

Safe Use: Use a file handle for better grip and control, and always push the file away from you.

Pliers: Used for gripping, bending, and cutting wire.

Combination Pliers:* General-purpose pliers for gripping and cutting.

Needle-nose Pliers:* Used for reaching into tight spaces.

Safe Use: Always use pliers that are in good condition, and avoid using them to cut very hard materials.

Scissors: Used for cutting fabric and paper.

Fabric Scissors:* Specifically designed for cutting fabric, with long blades for clean cuts.

Paper Scissors:* Designed for cutting paper and other thin materials.

Safe Use: Keep your fingers away from the blades, and cut in a controlled motion.

Basic Processing Techniques: Cutting Wood: Use a saw to cut wood to the desired size and shape. Important to measure correctly and cut along the marked lines.

Example:* Building a small wooden box. You would need to measure and cut the wood pieces to the correct dimensions using a handsaw or jigsaw.

Shaping Metal: Use a hammer and anvil to bend or shape metal. Also files can be used to smooth sharp edges after cutting metal.

Example:* Making a metal bracelet. You would bend a piece of wire into a circle using pliers, and then use a file to smooth the ends.

Joining Fabric: Use a needle and thread to sew fabric pieces together. A sewing machine can also be used for faster and more accurate stitching.

Example:* Making a simple tote bag. You would cut two pieces of fabric and sew them together along the sides and bottom to form a bag. Guided Practice (With Solutions)

Question 1: Identify the material best suited for making a durable and weather-resistant outdoor bench. Explain your choice.

Solution: The best material for an outdoor bench would be wood. Specifically, a hardwood like teak or treated pine would be suitable.

Explanation: Wood is strong and can support weight. Treated wood is resistant to rot and insect damage, making it suitable for outdoor use. While metal could also be used, it can rust and become very hot in the sun. Plastic might not be strong enough for a durable bench.