Lesson Notes By Weeks and Term v5 - Grade 7

Lesson Video

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Performance objectives

• Calculate perimeter and area of 2D shapes (squares, rectangles, triangles, circles).
• Describe different types of triangles.
• Calculate volume and surface area of cubes and rectangular prisms.
• Distinguish between 2D shapes and 3D objects, and identify their nets.

Lesson summary

This week, we delve deeper into the fascinating world of geometry, focusing on the properties of 2D shapes and 3D objects. Understanding these shapes and their characteristics is crucial because they are all around us – from the buildings we live in to the food we eat, and even the patterns in traditional South African art. This knowledge is not just about passing exams; it equips you with essential problem-solving skills applicable to everyday life, from calculating the amount of material needed for a school project to understanding spatial relationships in your community. We will be exploring the relationships between area, perimeter, volume, and surface area.

Lesson notes

2.1 2D Shapes: Perimeter and Area Perimeter: The perimeter of a 2D shape is the total distance around its outside. It's like building a fence around a field. You add up the lengths of all the sides.

Area: The area of a 2D shape is the amount of space it covers. Think of it as the amount of paint you need to cover a wall. We measure area in square units (e.g., cm², m²).

Formulas: Square: Perimeter = 4 × side Area = side × side = side² Rectangle: Perimeter = 2 × (length + breadth) Area = length × breadth Triangle: Perimeter = sum of all three sides Area = ½ × base × perpendicular height (the height must be at a right angle to the base)

Circle: Perimeter (Circumference) = 2 × π × radius = π × diameter Area = π × radius² (π ≈ 3.14 or 22/7)