Global climate change, referred to as climate change in this paper, has become an important planetary issue, and given that K-12 students have numerous alternative conceptions or lack of prior knowledge, it is critical that teachers have an understanding of the fundamental science underlying climate change. Teachers need to understand the natural and human-induced factors affecting climate, and the potential consequences, and ways to mitigate and adapt to climate change. This study focusses on assessing preservice and inservice teachers' knowledge about climate change at the beginning and end of an instructional intervention embedded in an elementary science methods course. This paper describes the development of an instrument derived from the constructive modeling approach framework. The four components of this approach (the construct map, items design, outcome space, and measurement model) are discussed. In addition, the instructional intervention is described along with findings from the study and an analysis of the instrument. (Contains 3 tables and 1 figure.)