I think the reason we fear the unknown is that we are left at the mercy of 'no information' and so we easily replace the object of our fear with our greatest fear, or we find a way of creating a relationship between our greatest fear and the subject at hand. Imagine what damage this causes when it is associated to learning!
A teacher walks into class and loudly announces that you have to pay attention for that class because he anticipates that you will all find the material foreign and difficult. He then begins by making reference to objects that you have never heard of before. About this or that and how this is bigger and better or brighter than that. You immediately begin to fear because you realise that you are not understanding what it is he is talking about. You seem alone because everyone seems to be understanding. You want to ask a question but you feel embarrased. No one else 'needs' to ask a question so there must be something wrong with you. You think back to the time you could not understand something that everyone discussed with glee. You were the odd one out. Fear begins to grip you. It is then that your greatest fear shows its ugly head... and makes the most out of you.
I therefore think that the teaching process should be a protective process, where the teacher seeks to protect the learners from the greatest fear... the fear of the unknown.