How could Jesus be taught of God if he is all-knowing?

Answer:

"So they were saying to Him, "Who are You?" Jesus said to them, "What have I been saying to you from the beginning? I have many things to speak and to judge concerning you, but He who sent Me is true; and the things which I heard from Him, these I speak to the world." They did not realize that He had been speaking to them about the Father. So Jesus said, "When you lift up the Son of Man, then you will know that I am He, and I do nothing on My own initiative, but I speak these things as the Father taught Me"" (John 8:25-28).

Since Jesus said they would have to believe that he is, it naturally led to the question of who Jesus truly was. Jesus only hinted at who he was, and the Jews chose not to accept the hint. But this whole discussion started when Jesus declared who he was: he is the light of the world (John 8:12). It is what Jesus has been stating all along, but they refused to accept.

Jesus stated there were numerous things he could say about them which would reprove or judge them, but those things are nothing more than what the Father has said. But they continued to not understand that Jesus was saying God was the one who sent him. However, Jesus said that when they lift him up, that is to crucify him, then they would know that Jesus is "I am," and that he was only doing the will of God, the Father and teaching the things that the Father told him to teach. He is not acting alone, God has always been with him, and he has been doing the things that please God.

Basically, Jesus' point is that his actions and his teachings did not originate from his own ideas. He is the Prophet that Moses had foretold about (Deuteronomy 18:18-19). As a prophet, his words are not his alone, but the very words of the Father.