The idea may be explained to the child orally with the assistance of necessary text
material in Braille.
- Perimeter of a square
The length of the boundary of any closed figure is called its perimeter. In the case of
a square, its perimeter equals four times the length of its side.
Thus, perimeter of a square = 4 ×^ measure of the side
In symbols, P = 4 a , where P denotes the perimeter and ‘a’ denotes the side.
To enable the child to understand the idea, first the child may be explained the
concept orally. Once the child is clear with the idea, provide him/her with a square
made of wood or plastic along with a piece of thread. Ask the child to measure the
lengths of the four sides by placing the thread on the sides of the square starting and
ending at the same point. Now ask the child to measure the length of the thread
which is the perimeter of the square. Then the child may be asked to fold the thread
to form four parts and find out that each part will be equal to the side of the square
thus enabling him/her to understand that the perimeter of a square is four times that
of its side.
- Perimeter of a rectangle
Perimeter of a rectangle is obtained by adding the measures of the length and width
and then multiplying it by 2.
That is, perimeter = 2 lengths + 2 widths
= 2 (length + width)
In symbols, P = 2l + 2b or P = 2 (l + b)
The procedure followed in finding the perimeter of a square may be followed in enabling
the child to understand the idea of the perimeter of a rectangle also. After finding
the perimeter of the rectangle, enable the child to conceptualize that its perimeter is
equal to twice the sum of its length and the width. The braille slate which is
