At the time of the prophet, muslims men and women were never too shy to ask the prophet about all affairs, including such private affairs as sexual life, so as to know the teachings and rulings of their religion concerning them. As Aisha, the wife of the prophet testified, "Blessed are the women of the Ansar (the citizens of Madina). Shyness did not stand in their way seeking knowledge about their religion."
The way the ladies asked the prophet-directly or through his wives is a proof that sexual matters were not taboo but were fully acknowldged and respected. "Shyness is part of the faith" as the prophet taught, but he also taught "There is no shyness in matters of religion" even entailing the delicate aspects of sexual life.
It is our firm belief that facts about sex should be taught to children in a way commensurate with their age as they grow up both by the family and the school. We emphasize that this should be done within the total context of Islamic ideology and Islamic teaching, so that the youth-beside getting the correct physiologic knowledge become fully aware on the sanctity of the sexual relation in Islam and the grave sin of blemishing such sanctity whether under Islamic law, or far more important in the sight of God.
In the end, it is better to ask about embarassing thing now than being punished for not doing it after death...