OK, I want you to read this article: http://www.wired.com/medtech/health/magazine/16-05/ff_wozniak
It is a long article, ostensibly about Piotr Wozniak, a Polish programmer who developed a learning software program called SuperMemo. But the article contains much more than that: It talks about the history of cognitive neuropsychology, of the "spacing interval" effect in how we learn and forget, the reason cramming does not work, the reason why repetition does work, and lot more. If you are not familiar with this idea, below is the so-called "forgetting curve" from the article
A lot of the way we teach is based on a complete ignorance of some very basic psychology. Students need to see material again, and the repetition needs to come at increasing, rather than fixed intervals. And then there is this (from the discussion of the components to log term memory - retrieval strength and storage strength. Emphasis is mine) -
One of the problems is that the amount of storage strength you gain from practice is inversely correlated with the current retrieval strength. In other words, the harder you have to work to get the right answer, the more the answer is sealed in memory. Precisely those things that seem to signal we're learning well — easy performance on drills, fluency during a lesson, even the subjective feeling that we know something — are misleading when it comes to predicting whether we will remember it in the future. "The most motivated and innovative teachers, to the extent they take current performance as their guide, are going to do the wrong things," Robert Bjork says. "It's almost sinister."
Student evaluations, anyone? Anyway read the article, it is terrific.