To ajsd: if school is still the same, then something is not working. He may well have a reading, or writing, or hearing, or even vision problem that has not been identified. Has he been fully tested for more then just adhd?
Kids give up because they just can’t do the work. The question above is looking at one reason why he cannot do the work. The other may be that his medication is really not allowing him to concentrate. You need to talk to his teacher to find out how he is doing/acting in class. Can he pay attention, does he stay on track, or is he tired and out of it? It may be that he is undermedicated. Concerta is a great med, but he might need an adderall based medication. And, of course, he might be overmedicated. That is why it is so important to get a feeling for how he is doing in class. This video by Dr. Charles Parker should also be helpful – https://www.youtube.com/watch?v=S0gir0CPLjo
And, of course, the other thing that can help at school is a 504 plan or an IEP. Does he have either one of these?
By the way, what grade is he in now?