In Sparta, the rearing of children was meant to prepare them to be members of Sparta's warrior society. This applied more to boys than to girls, but it had an impact on how girls were raised as well.
It is said that each infant born in Sparta was examined to see if it was fit. If it seemed weak, it was either exposed to die or sent to a helot family to become a slave. Those children that survived lived at home until age 7. At that point, the children left home to go to school. The boys were trained to be warriors. They were trained to fight and to obey and to be brave. It is said that they were not fed enough to encourage them to go out and steal, thereby learning stealth. Girls were not trained as rigorously, but they were made to do physical training and to learn some forms of fighting.
In short, children did not have the sorts of childhoods we expect today. Their rearing as aimed mostly at making them tough so that they could participate in the Spartan society.