Lesson Notes By Weeks and Term v5 - Grade 7

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

• Define and explain the design process.
• Identify and describe mechanisms like levers, gears, and pulleys.
• Classify materials based on their properties.
• Explain the importance of workshop safety.

Lesson summary

This week, we will revisit and solidify the key concepts covered in the beginning stages of Grade 7 Technology. Technology is all around us, from the cellphones we use to communicate to the infrastructure that provides us with electricity and clean water. Understanding technological processes and designs is vital for South African learners because it equips us with the skills to innovate, solve problems specific to our communities, and contribute to the country's development. For example, understanding simple machines can help us design better tools for farming, while knowing about materials can help us build more sustainable and affordable housing.

Lesson notes

2.1 The Design Process The design process is a systematic approach to solving problems and creating new technologies. It's not always linear – you might go back and forth between steps as you learn more.

Steps in the Design Process: Identify a Need/Problem: Recognize a need or a problem that exists. This could be something personal, something affecting your community, or something affecting the world.

Example: A school lacks a shaded area for students to eat lunch during hot days.

Research: Gather information about the problem, potential solutions, existing technologies, and materials. This involves asking questions, reading books, searching the internet, and talking to experts.

Example: Research different types of shading structures, materials suitable for outdoor use in South African weather, and local building codes.

Develop Solutions: Brainstorm and generate different possible solutions to the problem. Sketch ideas, create models, and explore different options.

Example: Drawing sketches of various shade structures using different materials like shade cloth, wood, or metal.

Create a Prototype: Build a working model or prototype of your chosen solution. This can be a simple, scaled-down version of the final product.

Example: Building a small-scale model of the chosen shade structure using cardboard, fabric, and other readily available materials.

Test and Evaluate: Test the prototype to see if it works as intended. Collect data, observe its performance, and identify any problems or areas for improvement.

Example: Testing the model in direct sunlight to see how effective it is at providing shade. Measuring the temperature difference under the model compared to direct sunlight.

Improve/Refine: Based on the testing results, make changes and improvements to the design. This may involve going back to earlier steps in the design process.

Example: Adding extra supports to the model shade structure to make it more stable, or choosing a different type of shade cloth that provides better UV protection.

Why it's important: The design process provides a structured way to solve problems creatively and effectively. It encourages innovation and helps us create technologies that meet real needs. 2.2 Mechanisms A mechanism is a system of parts working together to perform a specific function, often involving the transfer or transformation of motion and force. Understanding mechanisms is crucial for designing machines and tools.

Common Mechanisms: Levers: A rigid bar that pivots around a fixed point (fulcrum) to multiply force.

Example: A seesaw (balance scale) in a playground.* Formula: Mechanical Advantage (MA) = Load Distance / Effort Distance. If the effort distance is greater than the load distance, the lever provides a mechanical advantage, meaning less force is needed to move the load. Worked

Example: You use a lever to lift a rock. The fulcrum is 1 meter from the rock (load distance) and 2 meters from where you apply force (effort distance). What is the mechanical advantage? MA = 1/2 = 0.

5. While this is less than one, the distances have been defined in the opposite way that makes sense. Normally, the fulcrum would be closer to the load than the point of effort. if that was true, MA = 2/1 =

2. For every 1 Newton of force you apply, the lever multiplies it to 2 Newtons.

Gears: Rotating toothed wheels that mesh together to transmit motion and torque.

Example: Gears in a bicycle to change speed and force.* Gears can increase speed or increase torque (rotational force), but not both at the same time.

Pulleys: A wheel with a grooved rim around which a rope or cable passes. Used to lift heavy objects.

Example: A crane lifting containers at a harbor. Block and tackle systems in construction.* Pulleys reduce the amount of force needed to lift an object. The more pulleys in the system, the less force required, but the more rope you need to pull. Worked

Example:* A system utilizes 3 pulleys supporting the weight.

Therefore the weight is divided by three. If the weight is 300N, the required pull force is 300N / 3 = 100

N. Inclined Plane: A sloping surface used to raise objects. Requires less force to move an object up an inclined plane than to lift it vertically.

Example: A ramp used to load goods onto a truck.* 2.3 Materials and Their Properties Choosing the right material for a specific application is crucial. Different materials have different properties that make them suitable for different purposes.

Key Material Properties: Strength: The ability of a material to withstand force without breaking or deforming.

Example: Steel is a strong material used in building structures.* Hardness: The resistance of a material to scratching or indentation.

Example: Diamonds are very hard and used for cutting tools.* Flexibility: The ability of a material to bend or deform without breaking.

Example: Rubber is a flexible material used in tires.* Durability: The ability of a material to withstand wear and tear over time.