Many nature of science (NOS) studies have demonstrated that teachers can improve their understandings of NOS with explicit and reflective instruction; however, the field has relied heavily on qualitative methods. Because qualitative studies can be difficult to compare across studies and contexts, our study sought to determine if a quantitative instrument, Students' Understanding of Science and Scientific Inquiry (SUSSI) (Liang et al., 2008), could detect differences in NOS understandings that might make large studies and comparisons across studies easier. This study investigated changes in 60 elementary teachers' NOS views during a year-long extensive science, technology, engineering, and math (STEM) professional development program designed for elementary teachers. We found four NOS constructs (Social and Cultural, Collaborative, Creative and Imagination, and Scientific Method) out of the eight on the SUSSI had an acceptable Cronbach's alpha values and we found that quantitative assessment could detect interesting differences in participants' NOS views from pre- to post-assessment.