Rabbi Yosef Yitzchok of Lubavitch once told:
A child remains a child. On Rosh Hashanah of 1888, when I was a child of seven and several months, I visited my grandmother and she treated me to a melon. I went out to the yard and sat with my friends on a bench directly opposite my father's window and shared the melon with my friends.
My father called me in and said to me: "I noticed that you did indeed share with your friends, but you did not do it with a whole heart." He then explained to me at length the idea of a 'generous eye' and 'malevolent eye.'
I was so deeply affected by my father's words that I was unable to recover for half an hour. I wept bitterly and brought up what I had eaten of the melon.
"What do you want from the child?" asked my mother. Father replied: "It is good this way. Now this trait it will be ingrained in his character."
Concluded Rabbi Yosef Yitzchok: "This is education."