I have had many students who have been on ADHD medication including Concerta. I have seen it work wonders.
I would suggest that you not forget about the non-medication side of living with ADHD. I have seen the most improvement in students who were treated with a combination of medication, counseling and behavior modification.
Some suggestions that may help. Frequent breaks during assignments, alternate seating (I have something called a Wiggle Cushion -- a plastic, inflated cushion shaped like a wedge. Lets kids wiggle as needed while still remaining in their chair), shortened assignments, frequent progress checks with the teacher (child does 2 problems and then checks in, does 2 more and checks in, etc.)
Just an FYI -- schools must make accommodations for children with ADHD under Federal law
Good luck and God bless.