Final Cover - For Printing

The idea of improper set can also be explained to the child orally, supported by tactile

material depicting the sets.

18. Complement of a Set
    For a set A, its complement denoted as A’ (or Ac) is the set of elements of the
    universal set other than the elements of A.
    Eg. : If U = { 1, 2, 3, 4, ..., 9}
    A = {2, 4, 6, 8}
    Then, A’ = {1, 3, 5, 7, 9}
    To explain the concept to the child, ask him/her to consider the students of his/her
    class as a set. Therefore the universal set in this case is the set containing both boys
    and girls of the particular class. If A denotes the set of boys in the class then the
    complement of A is the set of girls in the same class.


19. Cardinal number of the power set of a set
    The cardinal number of the power set of a set is found using the formula, if n(A) = n,
    then the number of elements in the power set of A i.e., n[P(A)] = 2n.

For instance, consider the set A = {1, 2, 3}. Here, n(A) = 3. Then n[P(A)] = 2^3 = 8

Provide three objects (abacus, stylus and slate) to the child and ask him/her to group

the objects in various ways. The combinations are as follows :

C1 : {abacus, stylus, slate}

C2 : {abacus},

C3 : {stylus}

C4 : {slate}

C5 : {abacus, stylus}

C6 : {abacus, slate}

C7 : {stylus, slate}

C8 : { }