As a student, I found an easy way to keep my notes separated for each different class. At the beginning of school, I bought about ten dollars worth of the spiral one subject notebooks. I found them at the local Wal-mart and they were ten cents a piece. I used one spiral notebook per class and I placed all notes in them. When the class was over, I just placed the used notebook in the file cabinet with the folder that held all handouts.
Also, I always wrote the name of the class on the notebook and the folder. That way, I never got my class notes mixed up or lost the important information I needed. By staying organized, you will find your material that is needed for homework. There are some other ways to stay organized, like a three ring notebook that holds all your class notes. However, make sure that you use several paper dividers and mark them properly.