There are many different ways to introduce students to historiography. One of my primary tools is a "Historiography Worksheet." The purpose of the Historiography Worksheet is threefold. First, it teaches students about the complexities of historiography--as both a practice and a field of study. Second, it provides a framework for classroom discussion. Third, it offers students a standardized note-taking format that helps students develop their skills analyzing and synthesizing historical arguments.
The FILES folder contains PDF and ODT versions of the Historiography Worksheet as well as directions for students on how to fill out the worksheet.
For details on how I use the worksheet in class, see "Taking Notes Using the Historiography Worksheet."