Lesson Notes By Weeks and Term v5 - Grade 7

Lesson Video

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Performance objectives

• Identify and classify common basic materials.
• Describe the properties and uses of different materials.
• Identify and safely use at least five basic hand tools.
• Explain different processes for shaping and joining materials.
• Apply safety precautions when using tools.

Lesson summary

This week, we will explore the crucial area of processing basic materials using tools. Processing is a fundamental part of technology. It involves changing raw materials into useful products.

Think about it: the wood for your desk came from a tree that had to be cut, shaped, and joined. The metal in your cell phone started as ore dug from the earth and then smelted and formed. Understanding processing is key to appreciating the technology around us and even developing our own solutions to problems.

Lesson notes

What is Processing? Processing refers to the act of transforming raw materials into usable products or components. It involves changing the form, shape, size, or properties of a material through a variety of techniques.

Imagine a lump of clay: it's a raw material. Processing it could involve shaping it into a pot, firing it in a kiln to harden it, and then glazing it for decoration. All these steps are part of the processing.

Basic Materials: Let's consider some basic materials commonly used in South Africa: Wood: Wood is a natural material obtained from trees. It's strong, relatively lightweight, and easy to work with. Different types of wood (like pine, oak, and saligna) have different properties. Pine is soft and easy to nail, while oak is harder and more durable. In South Africa, wood is used for furniture, construction, and even fuel. Wood is processed by cutting, shaping, sanding, and joining.

Metal: Metal is a strong and durable material. Common metals include steel, aluminum, copper, and iron. Each has different properties. Steel is strong and resistant to rust (if stainless). Aluminium is lightweight and doesn't rust. Copper is an excellent conductor of electricity. In South Africa, metals are used in construction, vehicles, appliances, and electrical wiring. Metal is processed by cutting, bending, welding, and casting.

Plastic: Plastic is a synthetic material derived from oil. It's lightweight, versatile, and can be molded into various shapes. Different types of plastic have different properties. Some are flexible, while others are rigid. Plastic is used in packaging, containers, toys, and many other products. In South Africa, plastic recycling is a growing industry. Plastic is processed by molding, extrusion, and cutting.

Fabric: Fabric is a material made from fibers (natural like cotton or wool, or synthetic like nylon or polyester). It's flexible and can be woven or knitted. Fabric is used for clothing, upholstery, and other textiles. In South Africa, the textile industry is an important employer. Fabric is processed by cutting, sewing, and dyeing.

Tools for Processing: Tools are essential for processing materials.

Here are some common hand tools: Saw: A saw is used for cutting wood, metal, or plastic. There are different types of saws, like handsaws (for general cutting), hacksaws (for cutting metal), and coping saws (for cutting curves).

Hammer: A hammer is used for driving nails into wood or other materials. Different types of hammers have different weights and head shapes.

File: A file is used for smoothing and shaping metal or wood. Files have rough surfaces that remove small amounts of material.

Sandpaper: Sandpaper is used for smoothing wood or other surfaces. It comes in different grits (coarseness) – coarse sandpaper removes more material, while fine sandpaper creates a smoother finish.

Ruler/Measuring Tape: Essential for accurate measuring and marking before cutting or shaping. Accuracy is key to a good finished product.

Screwdriver: Used for driving screws into wood or other materials to hold pieces together. There are different types of screwdrivers for different types of screws (e.g., Phillips head, flat head).

Processes for Shaping and Joining: Cutting: Removing material to create a specific shape or size. For example, using a saw to cut a piece of wood to the correct length.

Bending: Shaping a material by applying force. For example, bending a metal rod to create a curve.

Joining with Fasteners: Using screws, nails, or bolts to hold pieces of material together. This is a common way to assemble furniture or other structures.

Safety Precautions: Always wear safety goggles to protect your eyes from flying debris. Use gloves to protect your hands from sharp edges or splinters. Keep your work area clean and organized. Never use a tool that is damaged or malfunctioning. Always cut away from your body. Ask for help if you are unsure about how to use a tool.

Example 1: Building a simple wooden box.

Material Selection: We choose pine wood because it's easy to work with and readily available.

Measuring and Marking: Use a ruler and pencil to mark the dimensions of the box pieces on the wood. Let's say the box is 20cm long, 10cm wide, and 5cm high. We need two pieces that are 20cm x 5cm, two pieces that are 10cm x 5cm, and one piece that is 20cm x 10cm (for the bottom).

Cutting: Use a handsaw to cut the wood along the marked lines. Remember to cut slowly and carefully.

Sanding: Use sandpaper to smooth the edges of the cut pieces. Start with a medium grit sandpaper and then finish with a fine grit.

Assembly: Use a hammer and nails to join the pieces together. Make sure the nails are driven in straight and flush with the surface. Place the bottom piece last.

Finishing (Optional): You can paint or varnish the box to protect the wood and give it a nice finish.

Example 2: Creating a simple metal bracket.

Material Selection: We choose a thin sheet of mild steel.