Parenting, with a mandatory babysitting internship, preferably all night with a sick kid. The class should be required before the students enter puberty.
(And the class should end with an extra unit on reliable birth control methods, which should cover the logic and statistics and biology requirements in a forum where no-one is going to ask, "so what?")
Nothing is easier than to denounce the evildoer; nothing is more difficult than to understand him. - Fyodor Dostoevski