9 Add to this that not only is religious instruction forbidden in the primary schools, but not infrequently attempts are made to induce those whose duty it is to educate the future generations, to become purveyors of irreligious and immoral teachings, thus obliging the parents to make heavy sacrifices in order to safeguard the innocence of their children. We bless with all Our heart these Christian parents and all the good teachers who help them, and We urge upon you, Venerable Brethren, upon the clergy secular and regular, and upon all the faithful, the necessity of giving their utmost attention to the question of education and the formation of the young, especially among the poorer classes, since they are more exposed to atheist, masonic, and communistic propaganda, persuading yourselves that your country will be such as you build it up in the children.
Source: Acerba Animi (Vatican.va)