Amy Welborn has a fairly comprehensive post on the decision by the bishops of Connecticut on the adherence to state law by Catholic hospitals in offering Plan B, a possible abortifacient under some circumstances, to rape victims.
This is an immensely complex subject. I have no doubt that eventually the Vatican will weigh in on this. Meanwhile the best course for the catechist at the parish level, is probably to explain that the issue is still theologically unresolved. If you don't understand the issues involved read Jimmy Akin's post. He is not advocating a position, but explaining, as best he can, the probable thought processes of the bishops.
Remember, as a catechist your job is to convey the teachings of the Church, and the teachings of the Church in detail on this matter are still unresolved. If you think my statement is untrue please read the linked articles to see why I believe what I've stated.
Remember if moral issues were easy we would not need saints the caliber of Thomas Aquinas to teach on them.