It's a great thing for him to get into at that age. He ought to actually have some muscle control by then and can really develop into a sharp martial artist if he is really focused. The biggest concern is the school that he goes to. I would highly recommend taking a look around at several clubs where youcan observe a class or two, and aactually see how they are run. Try to avoid ones in a shopping center, or ones that the instructor is under 30 and has something like a 6th or 7th degree black belt. It usually means he isn't highly trained or respected in the martial arts world, but rather paid for his belt. A general rule of thumb is that with Tae Kwon do or a Japanese Karate style is that it should be a minimum of 4-5 years to earn a black belt. After that, each degree should take at least that number of years to test for the next rank (ie a 3rd degree black belt spent 5 years to get 1st degree black, 2 more for second and 3 more for third.) After they reach 5th, which is master ranking, the degree is more based upon their teaching and contributions to the martial art. Ask the instructor what organization granted his ranking. For example, a Tae Kwon Do master should have his belt from other the World Tae Kwon Do Federation or United States Tae Kwon Do Grandmasters Society or another organizing body. Be wary of spending your money on some guy who claims his school is "a combination of X and Y" styles. You ought to be able to tell if it is worth the money to send your son to a certain school just by watching a few classes and sitting down with the instructor to find out his credentials and how he runs his club. Do not enroll at a place that seems unorganized, has a lack of clear discipline in a class, and seems to bounce from one thing to another in an hour class. There should be a clear flow and organization to the content of the class. When students are practicing techniques, see if instructors are actually correcting poor form, or are just counting and going through the motions. Martial arts classes are expensive and can be very beneficial if done right. If done poorly, then your sonwill just be tthe kid with enough knowledge and confidence to get himself into trouble.