The common root of these dreams is worry about being unprepared. It's not just forgetting there's an exam or a term paper due. Getting on the school bus and realizing you forgot to wear pants is another common variation. It totally makes sense teachers would have stress dreams from the other side of the desk. It's the first day and you didn't prepare *any* lesson plans, or there's 44 kids in the class, or you've been assigned the wrong subject, etc.