In addition to casebooks, hornbooks, and treatises, there exists an entire industry devoted to helping law students understand the law. It is not cheating to read these study aids. You are going to law school to understand the law, so take advantage of these tools.
Books and electronic services exist that correspond to your casebook and can help you master the concepts. Commercial outlines offer examples to shape your own outline. Bar review outlines provide similar material. Case briefs offer shortcut samples of briefs for individual cases. Questions-and-answer books with multiple-choice questions, short-answer questions, and hypotheticals exist for you to test your comprehension. Entire digital empires exist with one goal: to make you understand the law that you are supposed to be learning in law school.
Using these supplemental materials can help. If law school forces you to teach yourself the law, these sources can help guide that education. Of course, they can also provide a crutch so you do not do the other things you need to do to learn. If you only read the case briefs instead of the cases, you will not be learning the law. If you only copy the outlines instead of creating your own, you will not be learning the law. They are helpful tools. But you still have to do your own hard work and know the law. Remember, there will be no commercial outline for being a lawyer. There will be no case brief for a real case. Your future clients deserve more. You are the ultimate product being created by the law school, and you need to be good at your job.