This three book series is notable for its inclusivity and appealing to children who love sports. All three books includes coaches and players of both genders and multiple races. Karate Hour also includes a student using a walker (albeit just in the background in one photo). The illustrations are realistic and gorgeous - the children look like your son or daughter's friends.
The books take children through practice (or class, in the case of Karate Hour) from beginning to end. The prose is simple, descriptive, and rhyming, perhaps better for younger children - my 4 (nearly 5 year old) is a bit bored by the simplistic narration of what the children are doing, despite the fact that he is very athletic and takes similar classes himself. However, if he encountered these books at age 2 or 3 I think he would have spent much longer pouring over them.
(or request at your local library!)