Richard Bond of Virginia Wesleyan College (and co-editor of From Jamestown to Jefferson: The Evolution of Religious Freedom in Virginia, a great book on religion in early Virginia) describes what he has learned from history lessons that have not worked.
In this piece in the recent Perspectives in History he discusses:
1. An assignment in which students used Wikipedia to cheat.
2. An assignment in which students doing a role-playing game found it impossible to empathize with the Ku Klux Klan.
3. An assignment in a "History of Piracy" course in which students found it difficult to employ the skills of "context" and "contingency."
Learning from the above has been humbling, forcing me to realize that no
matter how much time I spend on an assignment, there will remain
problems that I have failed to consider. Yet, as most know, failures are
opportunities, especially in classrooms that are designed to be
student-centered. Assignment goals can be made explicit, and
conversations can be had between students and professors about how to
improve learning. Demystifying and diagnosing such failures can help
students to improve their own work; not only can they see such failures
are part of the educational process, but they can also think through how
to overcome them, certainly a marketable skill. Happily, sometimes
spectacular blunders lead to serendipitous results, and so I hope to
keep failing, repeatedly, in the years to come.