I’ve written a lot about one of my favorite lessons — have students do “What If?” history projects (see The Best Resources For Teaching “What If?” History Lessons).
There have been two recent articles written describing some of the benefits about looking at history from that perspective:
What If Counterfactuals Never Existed? Studying history with hypotheticals is from The New Republic. It first shares the negatives, and then provides counter-arguments.
History Without Hitler? appeared in The New York Times, and points out some ways this kind of thinking can be helpful related to Arab Spring.