if your kid is a dumbass in math, then you should send him here right away. although kumon does not have a traditional classroom setting, it is excellent in drilling math concepts and skills.
basically, you go there, sit down and begin a 5 page worksheet in math (based on your diagnostic skill level), and they have roving teachers/mentors that will help you when you raise your hand. after completion, you go to a grader, and you may leave if you complete it 100% with no errors. if you have errors, then you have to go back and correct the problems you made a mistake on.
this is a good place for grade school kids to continuously build upon their math skills by reptition and drilling.