Titus 2 says that the aged women are supposed to teach the younger women to be discreet and chaste.  What does that mean?  How do I teach my daughter this?

The word discreet comes from the word, discernment.  It means to be wary, cautious, taking everything into account before speaking or acting especially to avoid social disgrace or embarrassment, tactful; trustworthy so as not to reveal confidences.  (Genesis 41:33Now therefore let Pharaoh look out a man discreet and wise, and set him over the land of Egypt.
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Chaste means staying pure sexually before and after marriage (no extramarital affairs) and it can also mean pure in speech, thought and actions.   (2 Corinthians 11:2For I am jealous over you with godly jealousy: for I have espoused you to one husband, that I may present you as a chaste virgin to Christ.
See All...; 1 Peter 3:2While they behold your chaste conversation coupled with fear.
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The way to teach your daughter is by example and by talking to her and explaining in terms that she is able to understand (this will be different at different age levels) what God says about being trustworthy and treating others with kindness and about keeping herself pure and clean as a way of honoring,  pleasing and obeying God.  Teach her that to disobey God in these areas will bring a great deal of unhappiness into her life.  Make sure that you monitor what she is exposed to.  If she is watching television she will be getting all the wrong messages in these areas.