Research anecdotal stories in areas of your specialization to include in your history lectures. Since most historians spend considerable time reading primary source material, it is fairly simple to track down additional material that can be added to material found in the textbook. You can also find additional material by relying upon the example of authors who have written on subjects outside of the mainstream of history. One of the most popular books in this field of unknown history is James Loewen's "Lies My Teacher Told Me: Everything Your American History Textbook Got Wrong." Use the bibliography provided by Loewen to uncover additional material or use his stories as a way to illustrate how the class textbook is missing information that may be considered necessary material by some scholars.
Assign primary source reading as a part of your regular curriculum. One simple way to do this is to require students to purchase a history readings text that contains nothing but primary sources that students can read to gain first-hand knowledge of what was said or written in history. One source for this material is Michael Logan's "Visions of America's Heritage," a book of readings in American history that includes questions that students can answer about each selection to learn more about the process of historical inquiry.
Show film and other multimedia content in class that is not included in the textbooks. The History Channel is one good source for historical topics slightly out of the mainstream of the textbook treatment of history. The use of DVDs and audio tracks other types of material can provide a break from the more mundane subjects covered by the text. Create writing assignments associated with these videos or other material that require students to conduct additional research to delve more deeply into history source material not found in the textbook.