Earlier in olden days, the children were put in the Gurukulas to develop a very systematic way of learning in life until adulthood under the very able guidance of learned Gurus living close to them or living with them in the same house. Their strong devotion and submission to a beloved guru resulted in gain of wisdom, spiritual discipline and enlightenment.
This practice of Arsha Vidya Parampara (the knowledge tradition handed down by our sages/seers) developed individuals into healthy and intellectual citizens with timeless knowledge.