When does he have his core teacher vs the other teacher? If his other teacher has him at the end of the school day it could be his meds are wearing off and need adjusted. If that isn't the case then something else may be going on.
My son hasn't had any school issues related to his ADHD until this year which is 6th grade (has been on meds since kindergarten). His math teacher is complaining that he isn't paying attention. I thought math was at the end of the day and his meds were losing affect. It turns out math is in the middle of the day and language arts is at the end of the day and he has no problems with attention there. So it isn't his meds. Turns out he is really bored in math (his favorite subject) because they are moving at a snails pace according to my son.
One last thing, it is my understanding that when going through puberty, kids can be unorganized, forgetful, space cadets, etc.. So before changing his meds make sure you figure out what is puberty and what is his ADHD (I'm still trying to figure this out).
Good Luck!
Last April we put my 11 year old son on 5mg of Adderall XR. (He was 7 when tested for ADHD and depression.) His teacher saw a huge difference in his school work last year. Now he is in middle school (6th greade), his core teacher (who has been teaching for 1 year) says his attention level appears to be ok, his other teacher (teaching for 8 years) says, he his busy, cannot stay focused, organized, and has a hard time getting along with others. In her classes, he is missing assignments and receiving failing grades. In his core teachers class he is getting A's and B's. We are at a loss. Such opposite opinion from the teachers. Makes me wonder if his medication needs to be adjusted? Could the dose be to low? The things the 2nd teacher says are the things we have been hearing for years.