This study is a part of a bigger project known as the Science Writing Heuristic (SWH) Partnership Professional Development Project, conducted at Iowa State University and the University of Iowa in association with the Iowa Department of Education to help improve science teaching. Overall, the goal of the project is to help practicing science teachers understand and apply a student-oriented instructional approach, using the SWH. The purpose of this research study was to examine the link between teachers' implementation of a student-oriented teaching approach through the SWH approach with embedded non-traditional writing practices and students' performances on standardized tests over a 3-year period. This study investigated the impact of 6 teachers' (3 high school teachers and 3 middle school teachers) implementation of the SWH approach on student standardized test scores over the 3-year period. A mixed method approach was adopted as a research method;A major premise underpinning this study is that in the rate of change differs by teachers, and that change is not a linear process for teachers. Results of the study indicated a differential across teachers in terms of improvement in pedagogical skills related to the SWH approach. Further, results showed that the SWH approach in-service program did have an impact on participating teachers' pedagogical practices. The majority of the participating teachers improved their pedagogical practices of implementing science inquiry through the SWH approach over the 3-year period of the professional development program. Further, when teachers' rankings were correlated against students' standardized test scores, the results indicated that as their implementation levels increased their students' test achievements also increased.