Lesson Notes By Weeks and Term v5 - Grade 8

Lesson Video

This page supports the lesson note with a companion video and a short classroom-ready summary.

For class groups and homework, share this lesson page so learners also get the summary, objectives, and full lesson context.

Performance objectives

• Describe and apply the Design Process.
• Identify types of structures and the forces acting on them.
• Explain the properties of different materials.
• Identify the components of a simple technological system.

Lesson summary

This week's lesson focuses on revising and consolidating key Technology concepts covered in Grade 7 and the beginning of Grade

8. We will be focusing on design skills, structures, processing, and how these concepts are applied in everyday South African life. Understanding these fundamentals is crucial because technology is everywhere, from the cellphones we use to communicate to the bridges we cross. By mastering these basics, you will be better equipped to understand, use, and even create technologies that solve problems in your communities and contribute to South Africa's development.

Lesson notes

2.1 The Design Process The design process is a systematic approach to solving technological problems. It provides a structured way to identify a need, develop a solution, and test its effectiveness. The steps of the design process are iterative, meaning that you may need to go back and repeat steps as you learn more about the problem or your solution.

Investigate: This is the first step. You need to identify the problem clearly. What needs to be solved? Who is affected by the problem? What are the constraints (limitations) on your solution, such as budget, materials, or time? Research existing solutions, if any.

Example: Imagine your community experiences frequent power outages.

The problem is: "How can we provide a reliable source of light during load shedding?" You would investigate existing solutions like candles, paraffin lamps, solar lamps, and generators.

Design: Based on your research, brainstorm possible solutions. Sketch your ideas. Choose the most promising idea and develop a detailed design. Consider materials, construction methods, and safety. Include drawings and specifications.

Example: Based on the power outage problem, you might design a solar-powered lantern. Your design would include the size of the solar panel, the type of LED light, the battery capacity, and the materials used for the housing.

Make: Build a prototype of your design. Follow your design specifications carefully. Be safe!

Example: Build your solar-powered lantern using the materials you selected.

Evaluate: Test your prototype. Does it work as intended? What are its strengths and weaknesses? How could it be improved? Get feedback from users.

Example: Test the brightness and battery life of your solar-powered lantern. Ask community members for their feedback on the design and functionality.

Communicate: Share your design process and results with others. This could be through a written report, a presentation, or a demonstration.

Example: Present your solar-powered lantern to the community, explaining the design process, the materials used, and the results of your testing. 2.2 Structures A structure is something that has a definite size and shape and can support a load.

There are three main types of structures: Frame Structures: These are made up of separate parts joined together to support a load. Examples include bridges, towers, and bicycle frames.

Shell Structures: These are hollow structures that support a load by distributing the force over their entire surface. Examples include eggshells, bottles, and the hulls of boats.

Solid Structures: These are made of a single solid piece of material. Examples include tables, walls, and dams.

Forces on Structures: Structures are subjected to various forces that can cause them to deform or fail.

Tension: A pulling force that stretches or elongates a material.

Compression: A pushing force that squeezes or shortens a material.

Shear: A force that causes layers of a material to slide past each other.

Torsion: A twisting force.

Bending: A combination of tension and compression.

Example: Consider a bridge (a frame structure). The weight of the vehicles crossing the bridge creates compression on the pillars and tension on the cables. 2.3 Materials Properties The properties of a material determine how it will behave under different conditions.

Important properties include: Strength: The ability of a material to withstand a force without breaking.

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

Hardness: The ability of a material to resist scratching or indentation.

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

Example: Steel is strong and durable, making it suitable for building bridges and skyscrapers. Rubber is flexible, making it suitable for tires and hoses. 2.4 Systems and Control A system is a group of interacting parts that work together to achieve a specific goal.

Systems have three main components: Input: The information or energy that enters the system.

Process: What happens to the input inside the system.

Output: The result or product of the system.

Example: Consider a simple electric kettle.

Input: Electricity and water.

Process: The heating element heats the water.

Output: Hot water. Guided Practice (With Solutions)

Question 1: Describe how you would use the design process to create a device to help a visually impaired person navigate a busy street in a South African city like Johannesburg.

Solution: Investigate: Research the challenges faced by visually impaired people navigating busy streets. Investigate existing assistive devices (e.g., white canes, guide dogs). Identify the specific needs in the South African context (e.g., uneven pavements, heavy traffic).

Design: Brainstorm potential solutions, like a wearable device that uses sensors to detect obstacles and provides auditory or tactile feedback. Create detailed sketches and specifications for the device, including sensor types, feedback mechanisms, and power source.