Lesson Notes By Weeks and Term v5 - Grade 7

Lesson Video

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Performance objectives

• Define and give examples of different structures.
• Explain the parts of a technological system: input, process, output, and feedback.
• Identify renewable and non-renewable energy sources and their impact.
• Describe properties of materials and their uses.
• Apply the steps of the design process to solve a problem.

Lesson summary

This week's lesson focuses on revising and consolidating the key concepts we've covered in Technology throughout Grade

7. Technology plays a vital role in our daily lives, from the cellphones we use to communicate to the infrastructure that provides us with electricity and clean water. Understanding these technological principles empowers you to become informed citizens who can contribute to solving real-world problems facing South Africa, such as sustainable energy, improved water management, and effective waste disposal. This revision will reinforce your understanding and prepare you for future challenges.

Lesson notes

2.1 Structures: Structures are objects or systems that support loads or resist forces. They can be classified into three main types: Solid Structures: These are made of a single, solid piece of material. They are strong and stable but can be heavy and use a lot of material. Examples include brick walls, concrete dams (like the Gariep Dam), and clay pots. Solid structures withstand forces because the material itself is strong.

Frame Structures: These are made of interconnected members (e.g., beams, columns, trusses) that work together to support a load. They are lighter and use less material than solid structures. Examples include the Nelson Mandela Bridge in Johannesburg (uses steel beams), the roof of a shack made of wooden poles (a simpler frame), and bicycle frames. Frame structures are strong because the individual members distribute the forces across the entire structure.

Shell Structures: These are hollow, curved structures that are strong for their weight. They derive their strength from their shape. Examples include corrugated iron roofing sheets, the roof of the FNB Stadium (Soccer City), and the shells of eggs. Shell structures are strong because the curved shape distributes the forces evenly. 2.2 Technological Systems (Input, Process, Output, Feedback): A technological system is a set of interconnected components that work together to achieve a specific goal.

It involves the following elements: Input: The resources or information that enter the system (e.g., electricity, raw materials, instructions).

Process: The actions or operations performed on the input to transform it (e.g., a motor turning, a computer executing code, a factory assembling parts).

Output: The result or product of the process (e.g., light, a manufactured product, a completed task).

Feedback: Information about the output that is used to adjust the process and improve the system's performance (e.g., a thermostat adjusting the temperature of a heater, a sensor detecting low water levels in a dam).

Example (South African context): A solar water heater Input: Sunlight, cold water.

Process: Solar panels absorb sunlight, which heats the water in the tank.

Output: Hot water.

Feedback: A temperature sensor monitors the water temperature and adjusts the flow of water to ensure it reaches the desired temperature. 2.3 Energy Sources: Energy is the ability to do work. Energy sources can be classified as renewable or non-renewable.

Renewable Energy Sources: These are sources that are naturally replenished and will not run out. Examples include solar energy (from the sun), wind energy (from the wind), hydro energy (from water), and biomass (from organic matter like wood and agricultural waste). South Africa has significant potential for renewable energy, particularly solar and wind, which can help reduce our reliance on fossil fuels.

Non-Renewable Energy Sources: These are sources that are finite and will eventually run out. Examples include coal, oil, and natural gas. South Africa relies heavily on coal for electricity generation, which contributes to air pollution and climate change.

Environmental Impact: Renewable energy sources have a lower environmental impact than non-renewable sources. Burning fossil fuels releases greenhouse gases, which contribute to global warming. Renewable energy sources, such as solar and wind, produce little or no emissions. 2.4 Properties of Materials: Different materials have different properties that make them suitable for different applications.

Important properties include: Strength: The ability to withstand forces without breaking. Steel is strong and used in bridges.

Flexibility: The ability to bend without breaking. Rubber is flexible and used in tires.

Conductivity: The ability to conduct electricity or heat. Copper is a good conductor of electricity and used in wires.

Hardness: The ability to resist scratching or abrasion. Diamond is very hard and used in cutting tools.

Water Resistance: The ability to resist water penetration. Plastic is water resistant and used in containers.

Example: Choosing a material for a water pipe. PVC plastic is often used because it is water-resistant, relatively inexpensive, and easy to work with. 2.5 The Design Process: The design process is a systematic approach to solving problems and creating solutions.

It typically involves the following steps: Identify the Need: Define the problem you are trying to solve.

Research: Gather information about the problem and potential solutions.

Brainstorm Solutions: Generate a variety of possible solutions.

Create a Design Brief: Develop a detailed plan for your design, including specifications, constraints, and criteria for success.

Build a Prototype: Create a working model of your design.

Test: Evaluate your prototype to see if it meets the design brief.

Evaluate and Redesign: Identify areas for improvement and make changes to your design.

Communicate Results: Share your design and findings with others.