At our school, they require, from 4th grade up that all the kids use a 8 pocket folder. It's bound like a spiral notebook but has 8 pockets in it. I find them at the teacher supply store near us. It really works well for us and much better than the top entry, expandable type folder because we found that he would mistakenly put papers in the wrong slots, the tabs would fall off etc I have to say it really keeps my son organized. He doesn't have to remember *which* folder to bring home, because he has them all together in one book, so he just brings it home. He always has all his papers. If he wasn't putting papers in the folder, then we'd have a problem.
We also color coded books and spiral notebooks. So his science book has a green book cover on it and the spiral notebook that goes with it, is green as well. Same for math (red), English (blue) etc
Does your son use a daily planner to write out his assignments? Something else our school requires from an early age onward. It works really well. My 11 year has really mastered writing things down quickly, using his own abbreviations if necessary.
Have you talked to his teachers about his lack of organization and what they might recommend to help him succeed? You might just have to get in your child's head a little bit and figure out what's going on and why he's having so much trouble...
Good luck!
The folder we use looks like this:
http://www.holcombscatalog.com/produ...ducts_id=31147