An old piece of conversation

Five year  old niece: What are you doing for living
Aunt CDr: I am teaching Physics to adult students
Five year  old niece: What is Physics
Aunt CDr: Physics is a knowledge about energy
Five year  old niece: What is energy
Aunt CDr: Energy leaves tract to their case but no evidence. As an example, you can feel the coolness of grandma's air condition unit, but we cannot actually see the cool air.
Five year old niece: I don't understand a word you just said
Aunt CDr: Guess, I just drove her crazy.

.....a year later

Six year old niece: What is Physics
Aunt CDr: Physics is a specific subject about energy, just like mathematics is a specific subject about numbers and count.
Six year old niece: What is energy
Aunt CDr: Energy is a form strength that a particular thing has. Energy could be manipulated in many ways to benefit us. Example in medicine, in which I have particular interest in.
Six year old niece: I don't understand energy 
Aunt CDr: Erkk, wasn't it supposed to be 'I don't understand Physics', instead of energy. Yes, I did it again. Drove her crazy.

.... six months later

Six year and a half old niece:What is physics
Aunt CDr: Physics is a subject in school for adult students just like Mathematics, Science, English etc
Six year and a half old niece: Isn't Physics related to energy?
Aunt CDr: Yes, you absoulutely right
Six year and a half old niece: What is energy?
Aunt CDr: Energy is something you can feel/experience but  cannot see. Energy exists in many forms, liquid, solid or air. For example, can you see air?
Six year and a half old niece: No
Aunt CDr: Can you feel the temperature has been compromised everytime an air conditioner unit is switched on.
Six year and a half old niece:Yes
Aunt CDr: Well, that is physics
Six year and a half old niece: Grandma, do you want to know what is Physics
Aunt CDr: Guess she finally got it, after one and a half year.