He knows what He's talking about. And in this verse He's telling us how much we need Him, how much we need the Lord, teaching us how to become like Him, in being alive spiritually, in making an impact on people's lives as we reach out to them from day to day. A disciple is not above his teacher, but everyone who is fully trained will become like his teacher. Jesus is basically making three main points in this verse. He's establishing the wonderful reality that He is the leader to be followed.
Students follow the teacher.
They learn from the teacher. Parents guide their children. Sometimes in this society, unfortunately, we have a reversal of roles. Sometimes kids act like their parents, and their parents act like kids. This text tells us that Jesus is the teacher.