Information Anxiety - Remember what you forget

As I continue to re-read Information Anxiety (by Richard Saul Wurman) I continue to realize what an important book this is.  Teachers should especially read this book. Here's a provocative passage that applies to the teachers:

The most universal information trap is the one that inevitably occurs when attempting to communicate information.  It is the trap of forgetting what it's like not to know.  The minute we know something, we forget what it was like not to know it...We all fall victim to this when we explain something to another, because once we know something we can't remember what it was like not to know it.

This principle is so important to teachers, and yet it's so elusive. By the way, we're all teachers, aren't we?