For some of us, this seems counter-intuitive. We study like crazy to pass a test, take the test, and then forget everything immediately. Right?
Well, according to this study, that isn't entirely true. Generally, testing strengthens memory for items that are correctly recalled. The flip side of that is, the things you fail to recall become comparatively weaker. Restudying and retesting can remedy that, and help strengthen recall for those items that were weaker.
What interests me about this is that, as college students, we generally hate taking tests -- for the reason I mentioned before. It seems futile because we will only remember the information for the test and then immediately forget everything, not just the things we got wrong. I wonder why so many of us feel that way, and if it might be more an issue of not being asked to recall the information again. Thinking we've forgotten it because we haven't actively called it up again since.