It is essential for physical education teachers to utilize a foundation of physiological principles to design and monitor appropriate, safe, and effective exercise for their students. Adult training programs are not appropriate for children. Teachers should consider individual levels of maturation, motor skill ability, and affective needs when designing the program. The students' level of maturation, training experience, and ability should be considered in addition to grade level and chronological age when making decisions related to the level of exercise or type of program to implement. Introducing exercises early in a resistance training program teaches students how to control their body weight. Building a foundation of muscular strength and endurance at an early age, with a variety of movement experiences, can enhance human performance and prevent injury. The exercises described in this article can be included in physical education curriculums throughout elementary, middle, and high school. (Contains 9 figures.)