Curriculum fidelity describes the extent to which a curriculum is implemented faithfully as planned. Curriculum fidelity issues may arise when teachers implement the curriculum inconsistently due to differences in philosophy, barriers in the setting, or other local concerns.

It has been acknowledged in physical education (PE) that knowledge empowers learners to develop a physically active lifestyle In this study, we consider Cognitive Load Theory (CLT) as a valuable extension of the constructivist learning theory to help articulate the role of three pivotal instructional factors, content knowledge, learners, and instructional process, in learning fitness knowledge in PE. Guided by CLT, this study was intended to identify middle school students' cognitive architecture about aerobic and anaerobic concepts and pedagogical factors that might enhance or limit scientific conceptualization.