The concept of null set can be explained orally. If the child is not able to understand
the concept still, provide the child with an empty box with no objects inside. If the
box is treated as a set, then it is a null set with no elements.
- Universal set
A set which contains all the elements are under consideration is said to be a universal
set and is denoted as U.
Eg. : If A = {1, 2, 3}
B = {3, 4, 5}
Then, one of the universal sets for the above sets A and B is
U = {1, 2, 3, 4, 5, 6}
A group of sets can have any number of universal sets, the only condition being that
the universal set must contain all the elements which are under consideration.
To enhance the level of understanding, provide the child with a pencil, pen on one
hand and a slate, stylus on the other hand. The child is able to conceptualize that on
one hand he/she has writing devices for non-disabled pupils and on the other hand
he/she is having writing devices for the blind. Thus, one of the universal sets for the
objects which he/she is in possession can be the set of writing devices.
- Roster Form (or Tabular form)
In roster form, all the elements of the set are listed and are separated by commas.
Consider the set of vowels in the English alphabet. If C denotes this set, then,
C = {a, e, i, o, u}
This idea could be explained to the child orally, distinguishing the difference between
the different forms of representing a set.
- Set Builder Form
In set builder form, some property of the elements of the set is stated.
