A growing number of physical education teachers are introducing a new kind of P.E. in schools, emphasizing lifelong activities such as running, cycling, yoga, and skateboarding, in an attempt to make exercise more engaging--and lifelong--for elementary and middle school students. The new generation of P.E. classes is introducing youngsters to everything from step aerobics and yoga to inline skating and mountain biking. Experts agree that these approaches to exercise provide an attractive alternative to team sports and stay with students long after they leave school. The change from the traditional P.E. diet of dodgeball, volleyball, and jumping jacks is taking place as the fitness of today's youngsters, along with a looming obesity crisis, has become a central concern for educators and parents.