The Torah says, "You shall teach them to your children to talk about them, while you sit in your home, while you walk on the way, when you lie down and when you arise." (Deuteronomy 11:19).
The Torah commands us to teach our children to "talk about them" – them, the words of Torah – constantly. We would think that the command should say, 'you shall teach them to your children to talk about them, while they sit in your home, while they walk on the way, when they lie down,' and so forth. This is the seemingly logical way of teaching our children to live a life of Torah values, by speaking about and internalizing Torah and its teachings from morning to night, in everything they do. Yet, surprisingly, the Torah instructs the parent to teach them to discuss Torah while he or she sits in the home, walks on the way, and the like. What's the message that the Torah is conveying here?
The Torah is telling the parent that education is not preaching – it's personal example. A child's innate sense of justice cannot stand hypocrisy and inconsistency. A parent who preaches one thing yet practices otherwise is guaranteed to obtain the opposite results.
In simple English, if you live it, you can give it: if you don't live it, you can't give it. Therefore, before a parent educates his child, he must educate himself.
The principle of "live it to give it" is evident in the above-cited passage. Hashem is telling us that the best way to teach our children to be ethical and upright human beings is when we ourselves are ethical and upright human beings. If Dad cuts corners in business integrity, he has no right to scold his son for not telling the truth. On the other hand, when mom's Friday mornings are devoted to baking challas for poor families, her daughter will undoubtedly follow in her footsteps and engage in acts of lovingkindness as well.
Children have highest regard for parents, their chief role-models. As our sages teach, the deeds of parents are stepping stones for the children. If you live it, you can give it!