Classification of triangles
The set of 'triangles' can be subdivided into different types of triangles: equilateral, isosceles, right-angled and scalene. However, note that an equilateral triangle can be considered to be a special case of an isosceles triangle while a right-angled triangle can be either isosceles or scalene. It is important that pupils have their attention drawn to different ways of classifying the same shape. The diagram below summarises the classification of triangles:
Such classifications are quite hard for pupils to understand because any given shape may be classified in different ways.