An introduction to a Mystery teaching strategy. -- Mystery in history: guidelines and levels of investigation. -- Isn't history always a mystery?: objectivity and postmodernism, plus solving a minor mystery about the Vietnam War. -- Truer that true: looking at women in the Old West. -- Solved mysteries?: the case of Thomas Jefferson and Sally Hemings. -- Beyond the bare facts: exploring race and history through Thomas Jefferson and Hemings. -- Conclusion: Teaching history as mystery.