Grade 7 Technology (TECH) Summaries – Term 2 (Spot On)

This document provides a summary of the Grade 7 Technology (TECH) Summaries Term 2 (Spot On) Module 4 on Structures.

Module 4: Structures (P. 39-62) Focus Areas:

• What structures are.
• Types of structures.
• Design skills in creating structures.
• Stiffening structural materials.
• The effect of technology on society.
• Cell phone tower structures.

Unit 1: What are structures? (P. 40-41)

• Definition and Purpose: A structure is made to do a job, such as to support, protect, hold, or cover things. The purposes include to contain (hold in), protect (keep safe), support (hold up), and span (go over a gap).
• Classification: Structures are either manufactured (made by people) or natural (result of nature only).

Unit 2: Types of structures (P. 42-43)

• Three Basic Types:
  • Shell Structures: Usually curved, very strong, can span large areas without internal support, and spread pressure and stress. Examples: egg, domes, igloos, boat hull.
  • Frame Structures: Have a skeleton that supports the structure. They can be covered (e.g., houses, leaves) or open (e.g., spider web).
  • Solid Structures (Mass Structures): Made by piling solid materials, where each part supports the part above it. Examples: brick houses, rocks.

Unit 3-6: Other Key Concepts

• Triangulation: The use of triangles to strengthen a frame structure, making it rigid and stable by spreading force across all three sides.
• Stiffening Structural Material: Methods include Tubing (rolling material into a strong, hollow tube) and Folding (makes thin material stiffer and stronger, e.g., origami).
• Design Issues:
  • Stability: How well a structure stands, affected by the centre of gravity and base size. A larger base is harder to push over.
  • Reinforcing Techniques: Anything that makes a structure stronger.
  • Visual Pollution: Anything seen in the structure that causes harm, discomfort, or annoyance. Cell phone towers can contribute to visual pollution.
• Cell Phone Towers: Structures found everywhere in South Africa. They are sometimes disguised as trees, water towers, or cacti to blend in.