The relationship between teacher and student can take many forms. Modern educational approaches value the teacher insofar as he imparts information to the pupil. But traditional education is more akin to soul-nurturing. In the Theaetetus, Theaetetus is praised by his teacher Theodorus as a star pupil, but what we quickly discover is that Theaetetus lacks the courage and confidence necessary for learning, at least at this point. His soul has been lulled to sleep by Theodorus, a geometer of no little skill, but also a man lacking in wisdom. Theaetetus is caught in his shadow: he is a "yes-man" of the worst sort, totally dependant upon Theodorus and Socrates to do the real thinking for him.
Even worse, Theodorus seems to continue to be the "gate-keeper" for Theaetetus. He remains with Theaetetus throughout the dialogue, repeatedly pushing Theaetetus into conversation with Socrates and potentially hindering Theaetetus' development. They seem to intentionally avoid discussing whether knowledge and wisdom are the same thing, possibly to preserve Theodorus from the shame of being exposed as a knowledgable, foolish man. Theaetetus must go beyond his former master, but do so while Theodorus is present.
The dialogue is an appropriately terrifying reminder of the great power educators have over their students. We hold their souls in our hands, and it is ours to wake them up and help them to see, or to let them lie in their slumber. The charge for the educator is that we must become the sort of people that we wish to create, as we can not produce anything other than we are.
Theodorus' has been educated by a bad man and stands in need of redemption (to use Brian's fine phrase). Will Socrates be able to help him, or will his relationship with Theodorus prevent him from learning? This is the drama of education, and of the Theaetetus.