"And Hashem said, 'Will I conceal from Avraham that which I am going to do? For I am fond of him because he will educate his children and household to follow the ways of Hashem, to perform acts of charity and carry out judgement'" (Bereishis 18, 17 - 19 as per Rashi's explanation). Rav Wolbe comments (Shiurei Chumash) that it seems from this pasuk that Avraham's great righteousness and many acts of kindness were not a great enough merit for him to be worthy that Hashem reveal His plans to him. It was only educating his children to follow the ways of Hashem that earned him the extra fondness which in turn led to Hashem revealing His intentions with regard to the destruction of Sodom. From this we can deduce how great is the importance of chinuch and, therefore, we must make an effort to be sure that we are properly educating our children and pupils.