- Plane
A plane is a flat surface which extends endlessly in all directions. The concept may be
explained to the child orally. - Locus
Locus is normally associated with a moving point. The locus of a moving point is the
path traced out by it when it moves according to a specified geometrical condition.
Note that every point on the locus must satisfy the given condition. - Side
A side is a line forming the boundary of a plane figure. While explaining the concept of
any geometrical figure, the idea of side may also be explained. A circle has no sides
because it is a closed curve and hence its boundary is termed as circumference.
The idea may be explained with the provision of different geometrical shapes like
square, rectangle, rhombus, etc., made of hard board for the child to explore and
understand.
- Vertex
The point of intersection of any two sides of a geometrical figure is the vertex.
The concept of a vertex may be explained while introducing the concepts of square,
rectangle, triangle etc.
Here A, B and C are the vertices of the triangle^ ΔABC.
Side
ABC