TEACHER: Oxygen is a must for breathing & for life. It was discovered in 1773.
STUDENT: Thank God ! I am born after 1773 otherwise, I would have died without it.
TEACHER : What is an island ?
STUDENT : A piece of land surrounded by water except on one side.
TEACHER :On one side ?
STUDENT : Yes, on top
TEACHER :What's your name ?
STUDENT : Ravi
TEACHER : You should say "Sir"
STUDENT : OK, Sir Ravi !
