No two learners are the same. There are seven billion people in the world each with their own unique life experiences, which have in turn shaped their aspirations, their personality, their attitudes, their preferences and their capabilities. It goes without saying that one of the greatest mistakes we can make as designers of learning experiences is to treat them all as if they were the same. The most common manifestation of this, in my experience, is to provide the same solution for those with a great deal of prior knowledge as for those who are relative beginners. The outcome of this is typically that we over-teach the experts and under-teach the novices.