Bharat and Veda were two children aged seven and four respectively.
They lived with their parents and grandparents in a small house in
Chennai. The two children were having holidays and always wanted to
do something or the other.
It was a rather hot day, and it was too sunny to play outside. Mother was
very busy in the kitchen trying to get her cooking done. Grandfather was
reading the newspapers and grandmother was engrossed in her prayer
rituals.
Mother wanted to keep the two children busy and also wanted them to
be where she could see them. She did not want them to be up to some
mischief, so she asked them to help place the washed and dried kitchen
utensils in the shelves.
The children were happy to help their mother. They went about sorting
out the utensils and stacking them. Mother happily sang and cooked.
Mother now wanted them to hand over a vessel in which she wanted to
pour the sambar. “Mother one vessel is stuck inside the other “, said
Bharat. “I cannot separate them however hard I try”, he continued.
Mother was a little annoyed as she had to finish her cooking fast and she
did not want such diversions.

Mother was really busy. She had to finish a lot of work on time. “Go ask your grandma …she will tell you”, mother said.

The children ran to their grandma and told her all that happened. They were curious intelligent children and knew that there had to be a reason for all that they saw. It was no magic, there was a science to it.

 Grandma was always happy to sit with the children and talk to them about various things they saw. She believed that children learnt a lot by observation rather than by rote learning from books.

 “Children, when your mother heated the vessels on the gas, the heat reached the outer vessel first. It expanded and came away loose from the inner vessel.”

 “What is expansion?” asked little Veda.

 Grandma said that expansion meant that an object increased in size and occupied more space.

 “Why did the vessel expand on heating?”, asked Bharat who wanted to be a scientist and wanted an explanation for everything.

 Grandma said “Let us take a group of children who are standing in a line.

“Can you see that the line becomes longer if they start dancing?”

“Wow! The line has expanded!”, exclaimed Bharat.

“Now, the vessels are made of metal. The metal is made up of little particles called molecules. When the lower vessel is heated these molecules get extra energy, and they start moving to and fro with more vigour, taking up more space. “The lower vessel expands. The heat does not reach the inner vessel fast enough. It does not expand as much. It comes out free.”

By now Bharat already knew why this happened. He decided he would ask his mother to tell him why the ring did not pass through the ball when heated. He wanted to show off his newly acquired knowledge.