This study investigates whether teacher professional development is related to increased mathematics achievement in grade eight in Sweden and Norway from 2011 to 2015. In both Norway and Sweden efforts have recently been made to enhance teacher competence through professional development. Previous research has shown professional development to be related to student achievement, both directly and indirectly through instructional quality (e.g. Klieme et. al, 2009; Authors, 2016). Method Using data from TIMSS 2015 and 2011, we investigate the relation between teacher professional development, student-assessed instructional quality and 8th grade mathematics achievement in Norway and Sweden. A two-level (students and classes) two-group (Norway and Sweden) structural equation modeling approach was used, with a dummy variable for time (YEAR, coded 0 for 2011 and 1 for 2015). A mediation model was fit to investigate whether professional development and instructional quality may mediate the relation between YEAR and achievement. Results In Sweden professional development, instructional quality and achievement increased significantly between 2011 and 2015. In Norway only achievement increased. In Sweden, professional development was associated with instructional quality (β = 0.171, p<.001) which in turn was related to student achievement (β = 0.258, p<.001). In Norway, there was no significant relation between professional development and instructional quality, but there was a positive relation between instructional quality and achievement (β = 0.262, p<.001). In Sweden, professional development and instructional quality mediated the relation between YEAR and achievement (p<.05). Conclusion and implications In Sweden a large-scale national program for teacher professional development has been in operation since 2013, and the results suggest that this program has led to improved instructional quality, which in turn has improved mathematics achievement from 2011 to 2015. In Norway, neither professional development nor instructional quality has improved, which suggests that the increased level of achievement in Norway requires other explanations. Implications for educational policy and practice in Norway and Sweden are discussed.

Klieme, E., Pauli, C., & Reusser, K. (2009). The Pythagoras study: Investigating effects of teaching and learning in Swiss and German mathematics classrooms. The power of video studies in investigating teaching and learning in the classroom, 137-160