E) In the field of didactates

He promoted many innovations regardless of their origin. He did this in such a way that, as he later wrote in the Constitutions, "All care should be done in selecting the best methods among those proposed by experts and doctors in the matter."

He perfected the teaching of Latin and encouraged Fr. Juan Francisco to publish the first grammar book written in Italian. This practice would not become widespread for another one hundred years.t is ironic that while Comenius was writing his books in Latin urging the study of the mother tongue, Calasanz and his Piarists composed a grammar book in the vernacular language to study Latin.

Calasanz was also very concerned about effective preaching method,

"When preaching, especially for children, the Piarists should use only themes proper for the audience. They should meditate on waht they are going to say and prepare themselves, asking with humility for the Lord's help...Imitate the familiar style used by the Oratorian Fathers of the Vallicela...Refuse the affection of words and the emptiness of their contents...As much as you can, try to win the students for the srvice of God by the example of your life and with simple truths, mixed together with anecdotes about the saints."