Teaching response to WHY questions requires inferential skills - understanding of cause and effect. 

Going out Why do you go to the doctor? Because you are sick.
Why do you wear a jacket - because it is cold 
At home

Why do we put on the fan ? Because it is hot.

Why do we put on the light? Because it is dark. 

EatingWhy do you wash your hands after food ? Because it has food and is dirty
Why do you use a plate? to put the food in it.
Why do you need a spoon for ice cream - to be able to eat it
Why is the water cold? Because it was in the refrigerator
Why is the food hot - because we heated it in the stove
HygieneWhy do you comb your hair - because it is messy
Why do you brush your teeth - because your mouth smells in the morning
Why do you put oil in your hair - because it make the hair grow long
ActivityWhy do you play ? To have fun
Why do you want to paint brush - to paint the colours

Laundry / DishesWhy do we wash our clothes - because they are dirty or because they are clean?
Why do we wash the dishes - because they are dirty or because they are clean ?
EmotionsWhy is the baby crying - because his ice-cream fell down
Why is the girl crying - because she hurt herself