Hi, Rachel,
This sounds very frustrating! I was a teacher for many years, and saw this with a lot of parents. As another poster suggested, just talk to the teachers. I was always happy to help a child with organizational tasks. It was easy and saved a lot of frustration later on! : ) Also, have you looked up "executive functioning disorder"? It may not be what your son has, but you can find a lot of really helpful organizers/ checklists if you google that term.
A few suggestions for things you might do at home that may carry over to school:
-Try making checklists at home for things so that your child gets used to using them at home and at school. So, instead of just a checklist in his locker or cubby for homework, gym clothes, etc., he could also have one at home for bedtime (brush teeth, put clothes in hamper). That would give him some pride in independence and you some downtime!
-Get him separate notebooks for each class that are different colors, but keep them in one 3 ring binder, so he never comes home without the homework sheet he needs to fill out for the next day.
-Ask the teacher if he can check in with him/her at the end of the day to see if his daily homework is written down properly in his agenda. That's better than asking in class or at lunch, when everyone is rushing around.
I hope that some of this was helpful! Good luck!