The tips begin at a different place in each module. The advice moves along with the stages of the course.
You may think you've forgotten everything you learned from some of your undergraduate science courses, especially if you took them a long time ago. The problem, though, is that the memories are covered over, not that they are gone from storage. The speed with which we relearn things is strong evidence that we still possess the information in our unconscious. The brain needs only to revive these memories and refresh them for use. With a little work you can get back to where you were fairly quickly. Then you move forward!