"To meet this growing evil, God provided other agencies as an aid to parents in the work of education. From the earliest times, prophets had been recognized as teachers divinely appointed. In the highest sense the prophet was one who spoke by direct inspiration, communicating to the people the messages he had received from God. But the name was given also to those who, though not so directly inspired, were divinely called to instruct the people in the works and ways of God. For the training of such a class of teachers, Samuel, by the Lord's direction, established the schools of the prophets. Ed 46.1"
"And all Israel from Dan even to Beer–sheba knew that Samuel was established to be a prophet of the Lord."
Both passages discuss Samuel's role as a prophet and teacher. The EGW passage builds upon the biblical account by explaining Samuel's establishment of the schools of the prophets.