In physical activities, students' attitudes, values, and motivations change during their school years. Two theories concerning these changes are that teacher-student interactions and teachers' behaviors will differ according to the age level of the student groups and that evaluation of a teacher's effectiveness should be specific to the population being taught. Observations of physical education classes in elementary, junior high, and senior high schools for teachers' verbal and nonverbal behaviors suggest that both female and male teachers talk more frequently as students' grade levels increase. This is attributed to several possible reasons--the complexity of the material increases, a more analytical approach is used as skill levels increase, and a drop in motivation observed in older students calls for more intervention by the teacher. An observed tendency for student verbal communication to decline with age increase is thought to reflect, to some extent, a decline of childrens' spontaneity. Frequent positive reinforcement by the teacher is an important element at every age level. The affective aspects of physical education are directly linked to the students' lifetime involvement in sports and recreation long after the end of their formal schooling. (JD)