Lesson Notes By Weeks and Term v5 - Grade 4

Lesson Video

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Performance objectives

• Recognise, name and compare common 2D shapes.
• Describe the properties of 2D shapes (straight or curved sides).
• Identify and draw lines of symmetry.
• Complete a symmetrical figure from one half.

Lesson summary

Introduction: This week, we explore the wonderful world of 2D shapes and symmetry. Shapes are all around us! From the circular shape of a R5 coin to the rectangular shape of our classroom door, and the beautiful geometric patterns in Ndebele art, understanding shapes is essential. Symmetry is nature's art, seen in the perfect balance of a butterfly's wings or a protea flower. By learning about shapes and symmetry, we develop our spatial awareness, problem-solving skills, and our ability to see and appreciate the mathematical patterns in our beautiful South African environment and culture.

Lesson notes

What are 2D Shapes? 2D stands for 'two-dimensional'. A 2D shape is a flat shape that has only two dimensions: length and width. You can draw it on a piece of paper, but you can't pick it up like a box. Shapes with straight sides are called polygons.

Key Properties of Polygons: Sides: The straight lines that make up the shape.

Vertices (singular: vertex): The corners where the sides meet.

Let's look at some common polygons: | Shape Name | Example | Number of Straight Sides | Number of Vertices (Corners) | |-------------|------------------------|--------------------------|------------------------------| | Triangle | A slice of pizza | 3 | 3 | | Square | A window pane | 4 (all equal length) | 4 | | Rectangle | The South African flag | 4 (opposite sides equal) | 4 | | Pentagon | A school crossing sign | 5 | 5 | | Hexagon | A cell in a honeycomb | 6 | 6 | A Special Shape: The Circle A circle is a 2D shape, but it is not a polygon because it has one continuous curved side and no vertices. What is Symmetry? Symmetry is when a shape or object can be divided into two identical halves that are mirror images of each other. Think of it as 'balance'. The line that divides the shape into these two perfect halves is called the line of symmetry or the axis of symmetry. You can fold a shape along its line of symmetry, and the two halves will match up perfectly.