How to identify different 2D shapes | Year 4 Mathematics PDF Download

What are 2D shapes?

• 2D shapes are ubiquitous elements in our surroundings, appearing in various forms. 
• For instance, windows commonly exhibit a rectangular shape, while clocks typically feature a circular design. 
• These shapes are flat and possess distinct characteristics.

Properties of 2D Shapes

A property of a shape refers to a specific quality it possesses. These properties help us distinguish one shape from another. Some essential properties of 2D shapes include:

• Number of sides
• Number of vertices (corners)
• Length of sides
• Types of angles (acute, obtuse, right-angle)
• Presence of perpendicular and parallel lines

Let's examine the properties of three common 2D shapes - a triangle, a square, and a hexagon etc.:

Triangles

• All triangles consist of 3 sides and 3 angles. 
• The sum of their internal angles always equals 180°. 
• However, various types of triangles exist based on their properties, which include:
  • Isosceles
  • Equilateral
  • Scalene
  • Right-angled

Quadrilaterals

A quadrilateral is defined as a shape with 4 sides and 4 angles. Some examples of quadrilaterals along with their properties are:

Rectangle

• 2 pairs of equal sides.
• Angles all right-angles (perpendicular lines).
• 2 pairs of parallel lines.

Square

• A special type of rectangle.
• Sides all have equal length.
• Angles are all right-angles (perpendicular lines).
• 2 pairs of parallel lines.

Trapezium

• 1 pair of parallel lines.
• 2 sets of equal angles.
• 2 lines equal length and 2 that aren’t.

Kite

• 2 pairs of equal sides.
• 1 pair of equal angles.
• No parallel lines.

Regular Polygons

Regular polygons are shapes with all sides and angles equal. Let's explore some common examples:

Pentagon

• A pentagon has five equal sides and angles.

Hexagon

• A hexagon has six equal sides and angles, with three pairs of parallel lines.

Heptagon

• A heptagon features seven equal sides and angles.

Octagon

• An octagon consists of eight equal sides and angles, with four pairs of parallel lines.
  

Irregular Polygons

• Definition: Irregular polygons are shapes with sides and angles of varying sizes.
• Identification: Each polygon can be recognized by the number of sides it possesses. For instance, a pentagon always has 5 sides.
• Example:
  • This irregular pentagon features sides and angles of different lengths and sizes.
  • It includes two right angles and a pair of equal sides, while the other three sides have varying lengths.