Provide the child with a circular ring along with a piece of thread. Explain the idea
orally and then allow the child to measure the length of the outer boundary of the
circle with the help of the thread and measure the length of the rope using a scale to
find out the circumference of the circle.
- Semi circle
Semicircle means half of a circle i.e., both the parts are exactly identical. A thick
sheet of paper cut in the form of a circle may be given to the child to explore its
shape. Later, the same circle may also be cut across its diameter to make two semicircles
which are identical to each other.
To enhance the understanding level of the child, a sheet of paper in the shape of a
circle may be given to the child with an embossed marking of its center. Ask the child
to fold the paper along its center to form a diameter. Once folded, the circle becomes
a semicircle with the edge of the circular paper as the diameter of the semicircle.
- Area of a circle
Area of a circle can be found using the formula, A = π r^2 square units. The child needs
to be taught the formula clearly enabling him/her to know about the value of π
which is fixed and the value of ‘r’ which varies from circle to circle. Adequate practice
may be given to enable the child to find out the areas of circles with different radii.
- Area of a semicircle
A semi circle being exactly one half of a circle, the area of a semi circle is also exactly
one half of the area of a circle of the same radius.
Hence, area of a circle = π r^2 square units
Therefore, area of a semi circle = 2 r
π^2
square units
The idea may be explained to the child orally along with the provision of a sheet of
paper cut in the form of a semicircle.
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