The difficulty is the point (teaching critical thinking skills differs from teaching facts to memorize)
In the past few years I have seen more students who are very bright, hard-working, and grade-conscious, who are very comfortable when they have a list facts to memorize, or a formula to follow. Rather than thinking of a revision as an opportunity to develop, these students think more transactionally than organically about their learning, and prefer to see revision as a punishment for not getting it right the first time. I see it instead as an integral part of the critical thinking process.
