Lesson Notes By Weeks and Term v5 - Grade 7

Lesson Video

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Performance objectives

• Identify common materials and their properties.
• Describe processing techniques like cutting, shaping, and joining.
• Explain the safe use of basic hand tools.
• Apply these techniques to create a simple product.

Lesson summary

This week, we're diving into the exciting world of processing materials! Processing refers to changing raw materials into useful products.

Think about it: the wood used to build a desk, the metal used in a gate, or the clay used to make a traditional Zulu pot all had to be processed. Understanding how different materials are processed and the tools used for these processes is crucial. It allows us to appreciate the technology around us and even empowers us to create our own solutions to everyday problems. In South Africa, with its rich diversity of resources and cultures, understanding processing is especially important.

Lesson notes

2.1 What is Processing? Processing is the act of changing raw materials into usable forms. This can involve many different techniques, depending on the material and the desired outcome. It involves using tools and techniques to alter the physical properties of a material. For example, a raw log from a tree is processed into planks of wood used for building. 2.2 Common Materials and their Properties: Let's look at three common materials: Wood: Wood is a natural material obtained from trees. It's relatively easy to work with and is used in a wide range of applications from construction to furniture making.

Key properties of wood include: Hardness: How resistant it is to scratching or denting. Different types of wood have different hardness levels (e.g., pine is softer than oak).

Strength: How well it resists breaking under pressure.

Grain: The direction of the wood fibers, which affects how easily it splits or bends.

Durability: How well it resists rotting and insect damage. Treating wood can increase its durability.

Metal: Metals are strong, durable, and often shiny materials. They are used extensively in construction, manufacturing, and electronics.

Key properties of metal include: Strength: How well it resists breaking or bending under force.

Hardness: How resistant it is to scratching.

Malleability: The ability to be shaped by hammering or pressing.

Ductility: The ability to be drawn into wires.

Conductivity: The ability to conduct heat and electricity.

Plastic: Plastics are synthetic materials that can be molded into various shapes. They are lightweight, durable, and resistant to corrosion.

Key properties of plastic include: Flexibility: How easily it bends.

Strength: How well it resists breaking.

Heat Resistance: How well it withstands high temperatures.

Chemical Resistance: How well it resists being damaged by chemicals. 2.3 Basic Processing Techniques: Here are some common processing techniques: Cutting: Separating a material into two or more pieces. For wood, this could involve using a saw. For metal, a hacksaw or cutting torch might be used. For plastic, a knife or scissors could be sufficient.

Shaping: Changing the form of a material without necessarily removing any material. For wood, this could involve bending or carving. For metal, this could involve bending, hammering, or casting. For plastic, this could involve molding or vacuum forming.

Joining: Attaching two or more pieces of material together. For wood, this could involve using nails, screws, or glue. For metal, this could involve welding, soldering, or using rivets. For plastic, this could involve using glue, screws, or heat welding.

Finishing: Improving the surface appearance of a material and/or protecting it from damage. For wood, this could involve sanding, painting, or varnishing. For metal, this could involve polishing or painting. For plastic, this could involve polishing or applying a protective coating. 2.4 Basic Hand Tools: Here are some essential hand tools and their uses: Saw: Used for cutting wood, metal, or plastic. Different types of saws are designed for different materials and purposes (e.g., a hand saw for cutting wood, a hacksaw for cutting metal).

Safety: Always use a saw in a well-lit area. Secure the material being cut. Use a slow and steady sawing motion.

Hammer: Used for driving nails or shaping metal. Different types of hammers are designed for different purposes (e.g., a claw hammer for driving and removing nails, a ball-peen hammer for shaping metal).

Safety: Always wear safety glasses when using a hammer. Hold the hammer firmly and strike the nail squarely.

Screwdriver: Used for driving screws into wood, metal, or plastic. Different types of screwdrivers are designed for different types of screws (e.g., Phillips head, flathead).

Safety: Use the correct size and type of screwdriver for the screw. Apply even pressure while turning the screwdriver.

Pliers: Used for gripping, bending, or cutting wire and other materials.

Safety: Use pliers only for their intended purpose. Do not use pliers to cut hardened steel wire.

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

Safety: Secure the workpiece firmly. Use a slow and steady filing motion.

Example: Making a simple wooden picture frame: Material: Pine wood (easily available and relatively soft).

Tools: Hand saw, measuring tape, pencil, sandpaper, wood glue, clamps.

Process: Measure and mark four pieces of wood to the desired length. Use the hand saw to cut the wood pieces. (Cutting) Sand the cut edges to smooth them. (Finishing) Apply wood glue to the ends of the wood pieces. Join the pieces together to form a rectangle. (Joining) Clamp the frame together and let the glue dry. Sand the entire frame to smooth the surface. (Finishing) Optionally, paint or varnish the frame. (Finishing) Guided Practice (With Solutions)

Question 1: Identify the material and list two of its properties that make it suitable for making a traditional cooking pot (potjie).