Lesson Notes By Weeks and Term v5 - Grade 7

Lesson Video

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Performance objectives

• Identify and classify common materials
• Describe basic processing techniques
• Identify and use common hand tools
• Explain safety precautions
• Apply a simple finishing technique

Lesson summary

This week, we delve into the exciting world of processing basic materials! In South Africa, we rely on processed materials every day – from the food we eat to the clothes we wear and the buildings we live in. Understanding how materials are processed allows us to appreciate the work and technology involved in creating these essential items. Knowing about materials and tools also empowers us to be creative and resourceful, potentially leading to innovative solutions to everyday problems in our communities. Imagine designing a more efficient way to recycle plastic in your neighbourhood, or creating stronger, more affordable building materials for homes.

Lesson notes

What is Material Processing? Material processing refers to the different ways we change raw materials into useful products. This involves various techniques and tools to alter the material's shape, size, and properties to make it suitable for a specific purpose.

Think about it: a tree isn't ready to be used to build a desk. It needs to be processed - cut into planks, shaped, and joined together.

Basic Materials and Their Properties: Let’s look at some common materials and their properties: Wood: Wood comes from trees. It's strong, relatively lightweight, and can be easily shaped. It's commonly used for furniture, building structures (like roofs), and tools. Different types of wood (e.g., pine, oak, imbuia) have different properties, affecting their suitability for different tasks.

Example:* Pine is often used for building roof trusses because it's lightweight and strong enough to support the roof's weight.

Metal: Metals like steel, aluminum, copper, and iron are strong, durable, and often good conductors of heat and electricity. They're used in everything from cars and buildings to electrical wiring and cooking pots.

Example:* Steel is used in building construction because of its high tensile strength (ability to withstand being pulled apart).

Plastic: Plastics are synthetic materials made from polymers (long chains of molecules). They are lightweight, versatile, and can be molded into various shapes. Plastics are used in packaging, toys, furniture, and many other applications.

Example:* Plastic bags are commonly used for packaging groceries because they are lightweight and waterproof.

Clay: Clay is a natural earth material that becomes moldable when wet and hard when dried or fired. It's used to make bricks, pottery, and tiles.

Example:* Bricks are made from clay and used to build houses because they are strong, durable, and provide good insulation.

Textiles: Textiles are made from fibers (natural or synthetic) that are woven or knitted together. Examples include cotton, wool, nylon, and polyester. Textiles are used for clothing, upholstery, and other fabrics.

Example:* Cotton is a natural textile used to make clothing because it is soft, breathable, and comfortable to wear.

Basic Processing Techniques: Here are some of the fundamental methods used to process these materials: Cutting: Separating a material into two or more pieces using tools like saws, knives, or shears.

Example:* Using a saw to cut a wooden plank to the desired length for a table leg.

Shaping: Altering the form of a material using tools like hammers, chisels, or bending machines. This can involve bending, folding, or molding.

Example:* Using a hammer and chisel to shape a piece of stone into a decorative ornament. Using heat and pressure to mold plastic into a bottle.

Joining: Connecting two or more pieces of material together using techniques like gluing, welding, screwing, or nailing.

Example:* Using nails to join wooden planks together to build a fence. Welding metal pipes together to create a water pipe system.

Finishing: Applying a surface treatment to a material to protect it, improve its appearance, or enhance its functionality. This includes techniques like painting, varnishing, sanding, or polishing.

Example:* Sanding a wooden surface to make it smooth before applying paint. Painting a metal gate to protect it from rust.

Basic Tools: It’s essential to know the tools needed to process the different materials.

Here are some common hand tools: Saw: Used for cutting wood, metal, or plastic. Different types of saws exist (e.g., handsaw, hacksaw, coping saw) for different materials and cutting tasks.

Important:* Always use the right type of saw for the material being cut.

Hammer: Used for driving nails, shaping metal, or breaking materials. Different types of hammers exist (e.g., claw hammer, ball-peen hammer) for different purposes.

Important:* Wear safety glasses when using a hammer.

Pliers: Used for gripping, bending, or cutting wires and small metal parts.

Important:* Avoid using pliers on live electrical wires unless they are insulated.

File: Used for smoothing and shaping metal or wood. Different types of files exist (e.g., flat file, round file) for different shapes and tasks.

Important:* Always use a file with a handle.

Safety Precautions: Safety is paramount when working with tools and materials.

Always follow these precautions: Wear appropriate personal protective equipment (PPE): This includes safety glasses, gloves, and closed-toe shoes.

Use tools correctly: Read the instructions and use the tool for its intended purpose.

Keep your work area clean and organized: This reduces the risk of accidents.

Avoid distractions: Focus on the task at hand.

Seek help if needed: Don't hesitate to ask for assistance if you're unsure about something.

Environmental Impact of Processing: Processing materials can have significant environmental impacts.