National Standards for Physical Education (NASPE, 1995) has suggested that physical education should provide opportunities for enjoyment, fun and entertainment. Based on emotional interest theory (Harp & Mayer, 1997), It seems a reasonable assumption that promoting enjoyment, interest would motivate students involving in the class and then, enhancing their skill and cognitive achievement. The purpose of this study was to examine the extent of correlation among affective factors, physical involvement, skill and cognitive achievement in selected activity units (gymnastics, multi-games, volleyball, dancing, fencing, and fitness club) from two middle schools where their curriculum was taught in accordance with national standards. Randomly selected middle school students (N=104) were asked to rate their affective factors (Enjoyment, Novelty, Situational Interest) using Situational Interest Scale in each of randomly selected lessons. Physical involvement was assessed using each student’s total steps in each lesson measured by Yamax Digiwalker. Skill and cognitive achievement in each unit was assessed using the teachers’ summative evaluations on skill tests and written exams. Pearson-Product Moment correlation analysis was conducted to examine the relationship among affective factors, physical involvement, skill and cognitive achievement. The result showed that the participants in the study thought their physical education classes were fun and interesting. The means of situational interest and enjoyment in various units ranged from 13.64 (fitness) to 16.01 (gymnastics) on the aggregated 20-point scale. The physical involvement was associated with enjoyment (r ranged from .42 to .70, p<.01), novelty (r range from .35 to .52, p<.01), and situational interest (r range from .41 to .69, p<.01) in dance, gymnastics, fencing, multi-games, and volleyball. In addition, physical involvement was not correlated with skill and cognitive achievement. The results suggest that affective factors are associated with students’ in-class learning behavior. Positive affects (e.g., instant enjoyment, situational interest) may effectively motivate students to actively participate in the learning process. However, the positive association between affective factors and achievement was not observed in the data for all units. The disassociation may indicate (a) incoherence of the curriculum, in that motivated learners did not learn worthwhile content that was to be assessed, (b) the effect of seductive details, in that the learning process over-emphasized fun and enjoyment instead of the core content/information that should be learned.