This study analyzed the effect of Physical Best (PB) Curriculum on activity levels of children in physical education class. Activity levels of elementary school students (N=92, males = 50, females = 42) were recorded throughout six normally scheduled physical education class periods. Students participated in both traditional and PB curriculums and were asked not to change any physical activity and performance behaviors during data collection. Activity levels were recorded with movement tracking bracelets and heart rate monitors; which, provided averages for steps and time-in-target-zone (TZ) per class period. Paired sample t-tests were used to compare steps and TZ between the two groups. Overall, students did not record as many steps or time in target heart rate zone while participating in lessons that began with a PB warm-up. The differences of average steps and TZ recorded between PB and traditional curriculums were significant (p< 0.05) for all grades and gender, except third grade girls. The elementary school students in this study recorded, on average, fewer movements and spent less time in their target heart rate zone during PB activities than in their traditional activities. However, student knowledge of their own fitness outcomes may motivate them to be physically active outside of class.