The recreational courses are designed to help you get through them, and the written exams are written so that 10 year-olds can pass them. The certification agencies actually benefit when you pass the course, so they want you to pass. Keep the communications open with your instructor, and don't be embarrassed to ask questions. You don't have to memorize tables or learn any tricky math. Keep it simple and remember most diving is learned in the water, not in the classroom. Just relax and have fun because the courses are meant to be fun. You will be hooked when you start diving!