Over nine years earlier, on September 11, 2001, the author was concerned about how young people would come to understand what came to be called "9/11." The particular history class she was teaching then and for the nine years following is a Critical thinking history class that stresses the facts and evidence that historians use, and emphasizes the importance of evidence to back up historical analysis. Her questionnaire, thus, focused on "what happened," i.e., the evidence necessary for interpretation or analysis. She also asked the students how they learned about the event, in an attempt to help students evaluate bias in the interpretation of facts and evidence. She administered the questionnaire to twenty-one different History 101 classes in the next nine years, to a total of 864 students. In this paper, the author discusses the responses she received yearly from 2001 until the present. She also includes two sets of results from spring semester 2011--the first from the questionnaire she administered in the first couple of weeks of the semester as usual, and the second from the same questionnaire administered after the capture and death of Osama Bin Laden in May 2011. For the majority of the eight hundred students taking the survey over the last nine years, "not forgetting" about 9/11 is clearly not the issue--most do not remember 9/11 with any degree of accuracy, and few have been taught it. The author concludes that it is our challenge as history teachers to recognize this gap in their knowledge and to offer a remedy. (Contains 8 notes.)