Aha! is best after Huh?

Mysteries are powerful, Cialdini says, because they create a need for closure. "You've heard of the famous Aha! experience, right?" he says. "Well, the Aha! experience is much more satisfying when it is preceded by the Huh? experience."

Chip Heath & Dan Heath, Made to Stick: Why Some Ideas Survive and Others Die (New York: Random House, 2007), ch. 2 (quoting Robert Cialdini, social psychologist at Ariz. St. Univ.)

Cialdini believes that a major benefit of teaching using mysteries is that "the process of resolving mysteries is remarkably similar to the process of science." So, by using mysteries, teachers don’t just heighten students' interest in the day's material; they train them to think like scientists.

Id.