April 1, 2011
Teacher professional development is usually designed with the ultimate goal of improving student learning through improvements in teacher knowledge and practices, yet relatively few studies have examined the impact on student knowledge as a result of their teachers having participated in professional development. In the current study, we aim to understand the relationship between a high-quality, online professional development program for high-school biology teachers and students' content knowledge of genetics and evolution. The professional development program is intended to enhance high-school biology teachers' subject content knowledge, pedagogical content knowledge, and use of digital resources. In addition, we explore the moderating influence of program duration on student impact. The study included 1,110 students of 32 teachers who completed the professional development course in the summer, and 2,238 students of 55 teachers in a control group. We found that students in the treatment condition had a stronger rate of growth across the year in genetics and evolution content knowledge compared to the control group. We also found that stronger impact occurred with the slightly shorter, more focused version of the course. With this paper, we hope to contribute to the understanding of important predictors of students' biology achievement, as well as to highlight the importance of professional support for high-school biology teachers.