I agree punishment isn't the answer. Rather, the system you set up with the teacher is good. However, the stuff has to make it out of the classroom door and off the bus with him.
A 504 might allow you a second set of books at home. Then, you wouldn't have to worry about his forgetting the stuff. Also, would the teacher be willing to email assignments directly to you? Or, perhaps he has a buddy in the class whom he could call and double check it? Does anyone live near you who might have a book he can borrow on days that he forgets it?
My 10 year old son is in 5th grade. He has a fairly high IQ and does well in school. He is in advanced math class, and goes to the "learning support" room for tests (due to his GAD) and for writing assignments (due to dysgraphia). He also has ADHD. He was diagnosed with all this in early 2nd grade (almost exactly 3 years ago). We went through 4 different medications for him: Metadate: didn't help his attention and kept him up all night, Adderall: worked, but he lost 15% of his body weight and stopped growing, plus he complained his stomach hurt all the time. The doctor recommended we take him off it. Then we tried Focalin and Vyvanase. One made him paranoid (literally) and one didn't work. Unfortunately, we don't know if the stunted growth from the Adderall is permanent or temporary. He is now the exact same size as his 8 year old brother. People ask us if they are twins all the time. His 3rd grade teacher said he was focusing fine (he has primary inattentive, not hyperactive) and we took him off the medication. His 4th grade teacher said the same thing. What is a HUGE ongoing problem is forgetting his homework. He's been in school 5 weeks and at least once a week he either forgets to bring a homework assignment home, his agenda book home, a book he needs, etc. I've had two phone conversations with the teacher already, she decided to check his homework assignment book and make sure he has everything before he leaves school. This has been in place less than a week. Tonight he forgot his assignment book but thought he had it on the bus, so he either left it at school or left it on the bus. We've grounded him for forgetting his homework (last week he was grounded Tuesday-Friday), and now we're trying to decide whether to ground him again. I just can't understand how he forgets this stuff so much. We've talked about putting him on meds again. My son doesn't want to take them, my husband (who also has ADHD and is forgetful and medicated as a child) isn't all for them either. If there is no other choice, we will try medication again, but does anyone have suggestions to help him remember his homework? What might motivate him? Thank you for any ideas!! I think meds don't work for 10% of the people (?).