In the meantime, however, I would also suggest having your son evaluated for learning problems by your local district. You have the legal right to request this free evaluation. Contact your school guidance counselor to get more information about how to get this done. If you have difficulty, contact the Coordinated Campaign for Learning Disabilities (CCLD) at 1-888-GR8-MIND or go to their website at http://www.aboutld.org. They can guide you through the process.
If your son is already receiving services at the school, you should be getting regular updates about his progress. If he is not making progress under current conditions, it is the responsibility of the school to modify his program to give him the supports he needs to be successful. Both CHADD and CCLD should be able to help you in this matter.