Help your middle school students keep their binders organized by providing them all with a blank table of contents for their social studies binders (or binder section!). Each time you distribute a handout, assign it a number and have the students number it. Keep a master list on your wall.
For some additional support, keep a "sample binder" available in case kids forget to label something and want to see what a particular handout number "looks like". Another handy idea is to keep a milk crate with numbered hanging folders in your room. Keep extra copies of each handout in the appropriately numbered folders. Then, if a student is absent or loses a handout, they can easily access a copy without asking you!