Phenomena associated with the "pendulum" present numerous opportunities for assessing higher order human capabilities related to "scientific inquiry" and the "discovery" of natural law. This paper illustrates how systematic "assessment of scientific inquiry capabilities", using "pendulum" phenomena, can provide a useful tool for classroom teachers and program planners. "Structured inquiry", a technique of teacher-facilitated student inquiry involving direct interaction between students and natural phenomena, is presented as a way to establish student competence in applying "scientific inquiry capabilities" (e.g., conceptualizing variation due to error). This approach to "assessment" can heighten student curiosity and provide a concrete referent for complementary cultural, historical, and scientific instruction. The role of "assessment" in constructively shaping science education programs is considered.