Lesson Notes By Weeks and Term v5 - Grade 9

Lesson Video

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Performance objectives

• Recall and explain key concepts (systems, structures, processing).
• Apply the design process to solve problems.
• Analyze and evaluate existing technologies.
• Solve practical technological problems.
• Understand structures and forces.

Lesson summary

This week focuses on consolidating our understanding of the Technology concepts covered throughout the term and preparing effectively for the upcoming examination. Technology plays a vital role in shaping our world, especially in South Africa, where innovative solutions are needed to address unique challenges such as resource management, infrastructure development, and access to information. From renewable energy solutions tackling load shedding to agricultural technologies improving food security, understanding technological principles empowers you to contribute to a better future.

Lesson notes

Let's refresh our understanding of the essential concepts:

A. The Design Process: The design process is a systematic approach to solving problems and creating new technologies. It's not a rigid, linear process; often, you'll need to cycle back to earlier stages as you learn more.

The five main stages are: Investigation: This involves identifying the problem, understanding the needs of the user, and researching existing solutions. Consider the context – what resources are available, what are the constraints (e.g., budget, materials, time)? In South Africa, a design investigation for a water purification system would need to consider the specific types of contaminants prevalent in local water sources and the availability of affordable materials.

Design: This is where you generate possible solutions, brainstorm ideas, and create sketches or models of your proposed design. Consider different design criteria (e.g., cost, effectiveness, sustainability, aesthetics). For example, if designing a solar-powered phone charger for rural communities, you might explore different solar panel technologies and enclosure materials, considering their cost and durability.

Make: This involves building and testing your design. This is where your designs come to life! The making stage often reveals unexpected challenges and opportunities for improvement. If building a bridge model from cardboard, you might discover that your initial design lacks sufficient support and needs modification.

Evaluate: This is a critical stage where you assess your design against the initial criteria and identify areas for improvement. Consider the strengths and weaknesses of your solution. How well does it meet the needs of the user? How could it be made more efficient, cost-effective, or sustainable? Evaluating a prototype of a rainwater harvesting system might reveal that the filter needs to be upgraded to remove smaller particles.

Communicate: This is where you share your design and the results of your evaluation with others. Effective communication is essential for receiving feedback and improving your design. This could involve creating a presentation, writing a report, or building a prototype to demonstrate your solution.

B. Systems and Control: A system is a group of interacting components that work together to achieve a specific goal.

Examples: a bicycle, a computer, a water filtration plant.

Input: The information or resources that enter the system.

Process: What happens to the input within the system.

Output: The result of the process.

Feedback: Information about the output that is used to adjust the process.

Control: Mechanisms used to manage the process and maintain the desired output.

Example: A simple geyser system.

Input: Cold water, electricity Process: Heating the water Output: Hot water Feedback: Thermostat sensing the water temperature Control: Thermostat switching the heating element on/off to maintain a set temperature.

C. Structures: A structure is something that has a definite size and shape, that performs a function, and can support a load.

Frame Structures: Made up of individual members joined together to form a strong framework (e.g., a bicycle frame, a bridge).

Shell Structures: Provide strength and rigidity through their shape (e.g., an eggshell, a dome).

Solid Structures: Made from a single piece of material (e.g., a brick, a statue).

Forces acting on structures: Tension: A pulling force that stretches or elongates an object. (e.g., a rope pulling a load)

Compression: A pushing force that shortens or compresses an object. (e.g., a pillar supporting a roof)

Shear: A force that causes layers of an object to slide past each other. (e.g., scissors cutting paper)

Torsion: A twisting force. (e.g., twisting a screwdriver)

D. Electrical and Electronic Systems Series Circuit: A circuit where components are connected one after another along a single path. If one component fails, the entire circuit breaks. The current is the same through all components.

Parallel Circuit: A circuit where components are connected along multiple paths. If one component fails, the other components continue to function. The voltage is the same across all components.

Resistor: A component that limits the flow of current.

LED (Light Emitting Diode): A semiconductor device that emits light when current flows through it.

Switch: A device that can open or close a circuit, controlling the flow of current.