Lesson Notes By Weeks and Term v5 - Grade 7

Lesson Video

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Performance objectives

• Identify and classify basic materials like wood, metal, plastic, and clay.
• Describe material properties and how they influence tool selection.
• List and explain the function of common hand tools.
• Demonstrate the safe and correct use of at least three hand tools.
• Explain the importance of safety precautions when processing materials.

Lesson summary

This week, we delve into the exciting world of processing basic materials. Processing is the manipulation of raw materials to change their form, shape, or properties, making them useful for specific purposes. Think about turning raw clay into a beautiful traditional pot or transforming timber into sturdy furniture. This is crucial because the raw materials available in our environment aren't always in a form we can readily use. Learning about processing helps us understand how things are made, encourages innovation, and fosters problem-solving skills vital for contributing to South Africa's economy and development.

Lesson notes

2.1 What is Processing? Processing is the transformation of raw materials into more useful forms. It involves a series of actions that change the material's characteristics. For example, processing wood can involve cutting, shaping, joining, and finishing. 2.2 Types of Basic Materials Wood: A natural material derived from trees. Common South African woods include pine (often imported but widely used), Eucalyptus (widely grown commercially), and indigenous hardwoods like African Mahogany (though using this responsibly is key due to sustainability concerns). Wood is used for furniture, construction, and crafts.

Properties: strength, flexibility (to varying degrees depending on type), can be easily shaped.

Metal: Metals are mined from the earth. Examples include steel, aluminum, copper, and iron. Steel is widely used in construction and manufacturing. Aluminum is lightweight and used in packaging and transportation. Copper is an excellent conductor of electricity and is used in wiring. Iron is the base for steel and cast iron.

Properties: strength, hardness, conductivity (heat and electricity), ductility (can be drawn into wires), malleability (can be hammered into sheets).

Plastic: A synthetic material made from petroleum. Plastics are lightweight, durable, and can be molded into various shapes. Examples include polyethylene (used in bags and bottles), polypropylene (used in containers and fibers), and PVC (used in pipes).

Properties: lightweight, waterproof, can be molded easily, but can be environmentally problematic.

Clay: A naturally occurring material found in the earth. Clay is plastic when wet and hardens when fired. It's used to make bricks, tiles, pottery, and ceramics.

Properties: plastic when wet, hardens when fired, retains its shape. In South Africa, clay is readily available and used for traditional crafts and building. 2.3 Properties of Materials Strength: The ability of a material to withstand force without breaking.

Hardness: The resistance of a material to scratching or indentation.

Flexibility: The ability of a material to bend without breaking.

Durability: The ability of a material to withstand wear and tear over time.

Malleability: The ability of a material to be hammered into thin sheets.

Ductility: The ability of a material to be drawn into wires.

Conductivity: The ability of a material to conduct heat or electricity. 2.4 Common Hand Tools and Their Functions Saw: Used for cutting wood, metal, or plastic. Different types of saws include handsaws, hacksaws (for metal), and coping saws (for curved cuts).

Hammer: Used for driving nails, shaping metal, or breaking objects. Different types of hammers include claw hammers (for nails), ball-peen hammers (for metalworking), and rubber mallets (for delicate work).

File: Used for smoothing rough edges, shaping metal or wood, and removing burrs. Different types of files include flat files, round files, and triangular files.

Pliers: Used for gripping, bending, cutting, or twisting materials. Different types of pliers include combination pliers, long-nose pliers, and cutting pliers.

Screwdriver: Used for tightening or loosening screws. Different types of screwdrivers include flat-head screwdrivers and Phillips-head screwdrivers.

Chisel: Used for shaping wood or metal by removing small pieces.

Sandpaper: Used for smoothing surfaces. 2.5 Importance of Safety Precautions Safety is paramount when processing materials. Always wear appropriate safety gear, such as safety glasses, gloves, and closed-toe shoes. Use tools correctly and follow instructions carefully. Keep your workspace clean and organized. Be aware of potential hazards and take steps to mitigate them.