The dilemma is that it is impossible to shield children from lies. One potent source of modelling, however, is from within the home. Children, however, do not appreciate the nuances of a lie. Since it is difficult for parents to control the lies that children will encounter outside the home, it is more useful to start eliminating lies from within the home. Make telling the truth a priority both in instruction and by example.
Children also lie because they overpredict a reaction.
One of the most productive ways of addressing overprediction is to provide a child with clear boundaries, and yet emphasize that these boundaries are negotiable. Recall that one of the main motivators of lying is fear. Many children choose to lie because it seems the lesser of two evils, and they imagine they could get away with it. In a sense, lying is punishment-avoidant behaviour. In addition, there is the risk of confounding the message of the punishment.