Here's a great example of how children can benefit from martial arts training. This young karate-ka absolutely NAILS this kata for her age. Kankudai is not an easy kata to do well, and she shows excellent balance, control, and sharpness of movement.
While kata is just one aspect of karate, it is an important one. The confidence and fluidity of movement she shows here is exactly why I'm constantly saying that martial arts are great for everyone, but especially children.
A big "osu!" to this young woman.
(Aside: I still don't know how I feel about a black belt being awarded to such a young child, but perhaps it's not the same -dan ranking for children?)