The purpose of this study is to adapt the Professional Learning Activities Scale (PLAS) developed by Geijsel, Sleegers, Stoel, and Krüger (2009) into Turkish through conducting the relevant validity and reliability analyses. This study followed the pathway recommended by Hambleton and Patsula (1999) for the adaptation process. The data we used came from a total of 256 teachers working in 16 pre-schools, primary and secondary schools located in the Karabuk and Istanbul provinces of Turkey. We performed Exploratory Factor Analysis (EFA) and Confirmatory Factor Analysis (CFA) to test the construct validity of the Turkish-adapted form of the scale. In addition, Cronbach's Alpha coefficient was calculated for the reliability of the scale. The results of the study demonstrated that The Turkish Form of PLA is a reliable and valid instrument to evaluate the extent to which teachers are engaged in professional learning activities.

• Barth, R. S. (1990). Improving schools from within. Teachers, parents, and principals can make the difference. San Francisco, CA: Jossey-Bass.
• Bektaş, F., Kılınç, A. Ç., & Gümüş, S. (2020). The effects of distributed leadership on teacher professional learning: mediating roles of teacher trust in principal and teacher motivation, Educational Studies, doi: 10.1080/03055698.2020.1793301
• Bellibas, M. S., Bulut, O., & Gedik, S. (2017). Investigating professional learning communities in Turkish schools: The effects of contextual factors. Professional Development in Education, 43(3), 353-374. doi:10.1080/19415257.2016.1182937
• Borko, H. (2004). Professional development and teacher learning: Mapping the terrain. Educational Researcher, 33(8), 3-15. doi: 10.3102/0013189X033008003
• Brown, T. A. (2015). Confirmatory factor analysis for applied research. New York: Guilford publications.
• Byrne, B. M. (2010). Structural equation modeling with AMOS: Basic concepts, applications and programming (2nd Edition). New York: Routledge.
• Carmines, E. G., & Zeller, R. A. (1979). Reliability and validity assessment (Vol. 17). Thousand Oaks, CA: Sage. doi: 10.4135/9781412985642
• Chen, J. (2020). Understanding teacher leaders’ behaviours: Development and validation of the Teacher Leadership Inventory. Educational Management Administration & Leadership, 1-19. doi: 10.1177/1741143220945704
• Darling-Hammond, L. (2000). Teacher quality and student achievement: A review of state policy evidence. Educational Policy Analysis Archives, 8(1), 1-44.
• Darling-Hammond, L., & Richardson, N. (2009). Teacher learning: What matters? Journal of the Department of Supervision and Curriculum Development, 66(5), 46-53.
• Desimone, L. M. (2009). Improving impact studies of teachers’ professional development: Toward better conceptualizations and measures. Educational Researcher, 38(3), 181­199. doi: 10.3102/0013189X08331140
• DuFour, R. (2004). What is a professional learning community? Educational Leadership, 61(8), 6-11.
• Easton, L. B. (2008). From professional development to professional learning. Phi Delta Kappan, 89(10), 755-761.
• Flores, M.A. (2004). The impact of school culture and leadership on new teachers' learning in the workplace. International Journal of Leadership in Education, 7(4), 297-318. doi:10.1080/1360312042000226918
• Frost, D. (2006). The concept of 'agency' in leadership for learning. Leading & Managing, 12(2), 19-28.
• Geijsel, F. P., Sleegers, P. J. C., Stoel, R. D., & Krüger, M. L. (2009). The effect of teacher psychological and school organizational and leadership factors on teachers’ professional learning in Dutch schools. Elementary School Journal, 109, 406-427. doi: 10.1086/593940
• Geijsel, F. P., Sleegers, P. J. C., van den Berg, R. M., & Kelchtermans, G. (2001). Conditions fostering the implementation of large-scale innovations in schools: Teachers’ perspectives. Educational Administration Quarterly, 37, 130-166. doi: 10.1177/00131610121969262
• George, D. & Mallery, P. (2003). SPSS for Windows step by step: A simple guide and reference. 11.0 update (4th ed.). Boston: Allyn & Bacon.
• Gümüş, S., Apaydın, Ç., & Bellibaş, M. (2018). Adaptation of teacher professional learning scale to Turkish: The validity and reliability study. Journal of Education and Humanities, 9(17), 108-124.
• Hallinger, P., & Kulophas, D. (2019). The evolving knowledge base on leadership and teacher professional learning: a bibliometric analysis of the literature, 1960-2018. Professional Development in Education, doi: 10.1080/19415257.2019.1623287
• Hallinger, P., Liu, S., & Piyaman, P. (2017). Does principal leadership make a difference in teacher professional learning? A comparative study China and Thailand. Compare: A Journal of Comparative and International Education, 49(3), 341-257. doi: 10.1080/03057925.2017.1407237
• Hallinger, P., Piyaman, P., & Viseshsiri, P. (2017). Assessing the effects of learning-centered leadership on teacher professional learning in Thailand. Teaching and Teacher Education, 67, 464-476. doi:10.1016/j.tate.2017.07.008
• Hambleton, R. K., & Patsula, L. (1999). Increasing the validity of adapted tests: Myths to be avoided and guidelines for improving test adaptation practices. Journal of Applied Testing Technology, 1(1), 1-30.
• Hargreaves, A. (1994). Changing teachers, changing times: Teachers' work and culture in the postmodern age. London: Cassell.
• Hu, L., & Bentler, P. M. (1999). Cutoff criteria for fit indexes in covariance structure analysis: Conventional criteria versus new alternatives. Structural Equation Modeling, 6(1), 1-55. doi: 10.1080/10705519909540118
• Karacabey, M. F., Bellibaş, M. Ş., & Adams, D. (2020). Principal leadership and teacher professional learning in Turkish schools: Examining the mediating effects of collective teacher efficacy and teacher trust. Educational Studies, doi:10.1080/03055698.2020.1749835
• Kline, R. B. (2011). Principles and practice of structural equation modeling. New York: Guilford publications.
• Kwakman, K. (2003). Factors affecting teachers’ participation in professional learning activities. Teaching and Teacher Education, 19(2), 149-170. doi: 10.1016/S0742-051X(02)00101-4
• Leithwood, K., Dart, B., Jantzi, D., & Steinbach, R. (1993). Building commitment for change and fostering organizational learning (Final report for phase four of the research project, Implementing British Columbia’s Education Policy). Victoria: British Columbia Ministry of Education.
• Leithwood, K., Patten, S., & Jantzi, D. (2010). Testing a conception of how school leadership influences student learning. Educational Administration Quarterly, 46(5), 671-706. doi.org/10.1177/0013161X10377347
• Li, L., Hallinger, P., Kennedy, K. J., & Walker, A. (2016). Mediating effects of trust, communication, and collaboration on teacher professional learning in Hong Kong primary schools. International Journal of Leadership in Education, 20(6), 697-716. doi: 10.1080/13603124.2016.1139188
• Little, J. W. (1990). The persistence of privacy: Autonomy and initiative in teachers’ professional relations. Teachers College Record, 91(4), 509-536.
• Liu, S., Hallinger, P., & Feng, D. (2016). Supporting the professional learning of teachers in China: Does principal leadership make a difference? Teaching and Teacher Education, 59, 79-91. doi: 10.1016/j.tate.2016.05.023
• Ministry of Education [MoNE] (2018). Turkey’s 2023 Education Vision. Retrieved from http://2023vizyonu.meb.gov. tr/doc/2023_EGITIM_VIZYONU.pdf
• Mokkink, L., Terwee, C., Patrick, D. L., Alonso, J., Stratford, P. W., Knol, D. L., Bouter, L. M., & de Vet, H. C. (2010). The COSMIN study reached international consensus on taxonomy, terminology, and definitions of measurement properties for health-related patient-reported outcomes. Journal of Clinical Epidemiology, 63(7), 737-745. doi: 10.1016/j.jclinepi.2010.02.006
• Özdemir, N. (2020). How to improve teachers’ instructional practices: the role of professional learning activities, classroom observation and leadership content knowledge in Turkey. Journal of Educational Administration, doi 10.1108/JEA-10-2019-0189
• Qian, H., & Walker, A. D. (2013). How principals promote and understand teacher development under curriculum reform in China. Asia-Pacific Journal of Teacher Education, 41(3), 304-315. doi: 10.1080/1359866X.2013.809050
• Parise, L. M., & Spillane, J. P. (2010). Teacher learning and instructional change: How formal and on-the-job learning opportunities predict change in elementary school teachers’ practice. The Elementary School Journal, 110(3), 323-346. doi:10.1086/648981
• Sebastian, J., & Allensworth, E. (2012). The influence of principal leadership on classroom instruction and student learning: A study of mediated pathways to learning. Educational Administration Quarterly, 48(4), 626-663. doi: 10.1177/0013161X11436273
• Shengnan, L., & Hallinger, P. (2020). Unpacking the effects of culture on school leadership and teacher learning in China. Educational Management, Administration & Leadership, doi: 10.1177/1741143219896042
• Supovitz, J., Sirinides, P., & May, H. (2010). How principals and peers influence teaching and learning. Educational Administration Quarterly, 46(1), 31-56. doi/10.1177/1094670509353043
• Thompson, B. (2004). Exploratory and confirmatory factor analysis. Washington, DC: American Psychological Association.
• Thoonen, E. E., Sleegers, P. J., Oort, F. J., & Peetsma, T. T. (2012). Building school-wide capacity for improvement: The role of leadership, school organizational conditions, and teacher factors. School Effectiveness and School Improvement, 23(4), 441-460. doi: 10.1080/09243453.2012.678867
• Thoonen, E. E., Sleegers, P. J., Oort, F. J., & Peetsma, T. T., & Geijsel, F. P. (2011). How to improve teaching practices: The role of teacher motivation, organizational factors, and leadership practices. Educational Administration Quarterly, 47(3), 496-536. doi: 10.1177/0013161X11400185
• Vescio, V., Ross, D., & Adams, A. (2008). A review of research on the impact of professional learning communities on teaching practice and student learning. Teaching and Teacher Education, 24(1), 80-91. doi: 10.1016/j.tate.2007.01.004