I am inclined to agree with what Rita says here. I would perhaps further develop her thought that our Catholic schools are not Catholic in the true sense from the point of view of their educational practice. If Catholic education aims to promote a "synthesis of culture and faith" then all the different areas of the curriculum should be drawn into and presented from the point of view of a Catholic synthesis. This does not mean dogma is taught as science; it does mean that the science lesson relates to the Catholic vision of science. It does not mean Catholic doctrine is taught without any critical analysis or debate with other cultures or with scientific knowledge - that encounter and element of debate is of the essence of building a synthesis of culture and faith and therefore of Catholic schooling seen as an educational enterprise. In the context of sex education, it means that biology needs to be taught in synthesis with the philosophy of the human action, with ethics and with teaching about marriage as covenant and sacrament. In the language of John Paul II, the action of the person integrates the levels of the body with those of the spirit and of eternal life; in the language of Pope Benedict XVI, eros is purified to become agape. My experience suggests that, rather than a synthetic, cross-curricular vision that this requires, most Catholic schools teach their science lessons in this corner and their religious education in the opposite corner, and ne-er the two shall meet. However orthodox the teaching in religious education, it ain't goin' to work if it ain't applied in the science lesson, if the two pull in opposite directions. To put it another way: Catholic schools generally do not have science teachers who are sufficiently qualified and formed in the art of religious education, and vice versa, to effectively deliver sex education in an orthodox and pastorally effective manner.
The text of the letter quoted in this post is of interest, too, though I am not sure the gloss given to it is completely fair.
I feel sorry for Ed Balls and, in his shadow, Vernon Coaker. They seem to have said one thing to one constituency and a different thing to another constituency. And then sprung it on the unsuspecting public via an amendment tabled at Commons Third Reading - how cheeky was that!