Nightmares about struggling with school or exams happen all the time. Whether you're sat in a test, having written absolutely nothing, with only five minutes to go, or whether you realise it's the end of term and you haven't actually turned up to a class yet, being unprepared for assessments and in a position where failure is imminent. The apparently simple explanation for such nightmares is the fact that you are worried about your personal accomplishments in life. Perhaps you have made something of yourself and are afraid of losing it all, perhaps you haven't amounted to as much as you aspired to be when you were younger or perhaps you are worried that you haven't lived up to other people's expectations of you from when you were younger. Most commonly, these dreams are said to occur in people who have already made a success of themselves and manifest due to unnecessary insecurities so, if you're having them, you're probably doing okay.