My AP classes really did a good job with the two WPA slave narratives mentioned the other day. While a few of them pieced together that they were reading two accounts by the same person, they held back from spoiling it for everyone else. We analyzed the two sources and the students were asked to weigh the accounts based on their reading of the chapter in their textbook on slavery. As I mentioned earlier, the book we are using is Give Me Liberty! by Eric Foner and the chapter on slavery is one of the most sophisticated treatments of the subject to be found in a textbook. Once they understood that both interviewees were the same person we talked about how the interviewer could have influenced the narrative. In the case of Jessie Butler students wanted to know her age, where she lived, her racial views, etc. In the case of Susan Hamilton we discussed her interests in telling a story that sounded very much like the paternalistic accounts that slaveholders told themselves during the antebellum period. Did she hope to receive additional funds from the government or perhaps she worried that a negative portrayal of slavery would have placed her or her family in danger. All in all the lesson went very well.
You can find these interviews online at the Library of Congress. I would also recommend After The Fact: The Art of Historical Detection by James W. Davidson and Mark H. Lytle for interpretation. This is an incredibly useful book for the classroom as it takes you through various historiographical and interpretive challenges. Chapters include the uses of psychohistory, selection of evidence, the role of mass and photography in shaping popular perception, and the use of models in history. The only drawback is the price, which stands at a whopping $60 if you buy it new. Amazon lists some used copies and you should be able to find an old edition at a decent used book store.