[Note: As of June 10, 2016, this post has been updated—once and for all—to 12 Cs. You can find the update at this link. – TL]

With apologies to Thomas Andrews and Flannery Burke, who first introduced me to their “Five Cs of Historical Thinking” through a January 2007 column in AHA’s Perspectives magazine, I have developed a modification of their mnemonic that may be useful to my colleagues in history. I think this may be particularly helpful for introducing the field to new students—to those first-year undergraduates who think about “social studies” rather than history. In addition to Andrews and Burke, I also want to acknowledge Sam Wineburg for his classic work on this subject, Historical Thinking and Other Unnatural Acts (2001).

Rather than just “Five Cs,” I think we should add four more and emphasize the ‘s’ such that the mnemonic becomes “The Nine Cs.” It’s…