Challenges for students - teaching historiography

The great challenge in having students think historiographically is that they are unsure of how to confront the "objectivity question."  Students often come to 9-12 history classrooms thinking of history as some series of facts, chronologically situated, with absolute outcomes derived from clear cut causes.  We have a tendency to hammer home characteristics of founders, we paint vivid but unchallenged pictures of the course of human events, and we line up those events as if we are marching through time.  They are sometimes presented with the moral dilemmas of history, but often come out of those discussions with a sense of right action as if there was a right and wrong and no gray area.  They struggle to think that the telling of the story is as important as the story itself.  They find it unconscionable that an historian would write what they think happened rather than what "actually" happened - that history itself is uncertain.  They are in pursuit of Joe Friday's, "Just the facts ma'am" and don't realize that history is as much about the historian and the historian's time as it is the time the historian is writing about.

In order to help students confront the central problem of historiography, objectivity, what steps must the history teacher take to assure they are "developmentally" prepared to engage in historiographical discourse?  In other words, how might you as a teacher intent upon using historiography in your classroom help prepare students to engage in discourse about historian objectivity (or lack thereof) and historiographical context?  Post your response as a comment below.