Student or Learner
Let's say an English course is divided in 6 books. After each book there are final tests, and, of course, a student will only be able to start the following book after passing the previous one. In order to graduate, the student has to finish book 6. If the student happens to fail one of these books, let's say, book 4, would it be right to say that he will have to "repeat the book"? If it sounds strange, how could I say it?
Repeat that segment, repeat that section, repeat the coursework.
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.