Ignorance is an aspect of the manner in which we learn as humans. We must ACQUIRE knowledge. But the Word Himself has all knowledge INNATELY. The humanity of Christ does not cease to need to acquire knowledge. But RECEIVES all knowledge by the union with the Word. Thus he is truly human in that his knowledge must be acquired, but he receives all knowledge at the point of union, just as he is entirely holy, and entirely wise. He does not learn wisdom by trial and error. He is himself the Word of Wisdom and the Word of Knowledge.
There is however a very real point at which the psychology of Christ should not be investigated. We do not know. We should not presume.