Since starting college how I organized my classwork has changed drastically. Folders and spirals for the first time in forever (they'll be music, they'll be fun... sorry but I couldn't resist a Frozen reference).
And this new system really works well for me. It's much friendlier on my back! Now that I'm carrying around so many textbooks, binders were really out of the question. Although I have had at least one "looseleaf textbook" each semester due to the sheer size of the book (this semester it's actually just 100+ page financial report we're working with all semester); in which case I would only put a spiral and the chapters we were working on in it.
But in High School, I used a very different system that I loved. Each class had a binder and each binder was set up the same way using 5 dividers with tabs.
The first divider was labelled "To Do" and is exactly what the name implied: it housed my homework for that night which was often a worksheet or packet section. I also put any homework calendars, monthly/unit overview sheets, or project rubrics here. (Once my homework was finished I would put it right before the "To Do" so it was easy to find.)
The second divider was labelled "Current Topic" and is, again, very self explanatory. Any notes, handouts, or finished homework from the chapter or unit being worked on went here and was always in chronological order.
The third divider was labelled "Past Topics." Basically once we were tested on the "Current Topic" that section was moved here. This was really nice when it came time for midterms/finals because all the notes were here and uncluttered.
The fourth divider was labelled "Reference." This was almost always the smallest binder section and usually housed the course syllabus and anything that would be used consistently throughout the semester. Some examples being the Periodic Table in Chemistry, formula sheets in Physics or math classes, special grammar handouts for French, etc.
The final divider was labelled "Paper" and you guessed it, it had plenty of looseleaf stocked up.
This method was fantastic because I always knew where to find my homework (both To Do and to turn in), to look for notes from last class, and to not worry about misplacing my syllabus because they were in their assigned spots.
What do you use for your class organization system?