I truly understand the teachers' frustrations, but I'm not sure what tactics to use to try to help him remember things. He literally carries every book from every class all day rather than using his locker so that he doesn't forget things in his locker. His backpack is so heavy, it is hard for me to pick up. But if he forgets something in his locker, he is often given a zero because he didn't come to class prepared, so this is his solution.
Could you ask the school to borrow second copies of the textbooks as an accommodation, or can you buy them yourself?
