What is the plan for getting him from middle school back to the elementary school? (For that matter, how does he get to the middle school?) Does he get a locker there, or is he going to have to lug everything with him, and is the middle school teacher ok with that? (Some middle schools here have rules about how much you can carry with you to class, saying that you have to use your locker for excess stuff.)

What is the plan for days when the middle school schedule changes for some reason? This seems to happen all the time for assemblies or holiday adjustments or whatever. If the time at middle school doesn't overlap perfectly with elementary school math time, how will he make up any material covered while he is not there? What will he do if he is at elementary school while they are doing math? Does the middle school ever have "parallel" assignments where, say, they are doing the same stuff in math and in science, and how will they handle it if he is in the math class but not the science class?