Part of the challenge of keeping an organized binder is getting the student motivated to do so. Increase your fifth-grader's motivation by allowing him to make his binder his own. Select a binder with a plastic cover under which your student can slip a sheet that he has designed, and allow him to decorate this cover. Instead of leaving dividers plain, let the student decorate them with stickers or hand-done drawings.
Start your binder setup by creating a section for each subject. If possible, place these sections in the order in which your child will get to the subjects throughout the day. For example, if your child's teacher informs you that he will always start with math, then move to reading, place these two sections in this order.
Increase the likelihood that your student always has what she needs close at hand by putting storage into her binder. Purchase a pencil pouch and load it up with pencils, pens, erasers and a pair of school scissors. With these supplies close at hand, your child can spend more time focusing on her lessons and less time worrying about where she placed her pencil.
An efficiently organized binder is useless if the student doesn't use the system prepared. Help your fifth grader as he works to get used to keeping his papers in order by sitting down with him daily and helping him sort his papers into the proper sections. Keep plastic paper rings on hand in case the student has torn out any of his papers and you need to fix the holes before slipping them into his binder.
Your student likely does not need every paper she has ever gotten in her binder. At the end of each quarter, move through your student's binder and remove her old papers. If your child's teacher gives you the go-ahead, pitch these papers. If not, store them in a different notebook for later reference.
As your student becomes more adept at using the binder system, reward him for it. Give him stickers or small prizes each time he brings home an organized binder, showing him how much you appreciate his efforts towards organization.