The Interconnected Model of Professional Growth as a means to assess the development of a mathematics teacher Martha Witterholt a, * , Martin Goedhart b , Cor Suhre a , Anno van Streun b a University Centre for Learning & Teaching, University of Groningen, Landleven 1, 9747 AD Groningen, The Netherlands b Faculty of Mathematics and Natural Sciences, University of Groningen, Nijenborgh 9, 9747 AG Groningen, The Netherlands article info Article history: Received 26 April 2011 Received in revised form 2 January 2012 Accepted 9 January 2012 Keywords: Professional development Practical knowledge Teaching practice Modelling teacher change abstract In this qualitative study we used a case study approach to observe and analyse a mathematics teacher who was challenged to redesign her lessons during network meetings with colleagues. Changes in practical knowledge are described by means of concept maps and semi-structured interviews. We applied cycles of change from the Interconnected Model of Professional Growth to describe the teacher’s professional development. We show that the teacher’s practical knowledge changes in the domain of practical content knowledge, and that controlled experimentation and reflection are necessary condi- tions to learn a new teaching strategy and to develop a series of lessons for pupils. Ó 2012 Elsevier Ltd. All rights reserved. 1. Introduction Recent developments of the mathematics curriculum in Dutch secondary schools and more attention to inquiry-based teaching in (statistics) education have made it increasingly important for teachers to be able to redesign their teaching practices. This development aligns with similar changes in other countries. According to Sowder (2007 , p.157) several U.S. surveys reported that “improving the quality of teaching is the most important way to improve public education”. Much of what teachers need to learn must be learned in and from practice (Hammerness, Darling- Hammond, & Bransford, 2005), and well-designed professional learning helps teachers to address changes needed in teaching and learning (Darling-Hammond, Chung Wei, Andree, Richardson, & Orphanos, 2009). Past research (see Clarke & Hollingsworth, 2002; Fullan & Stiegelbauer, 1991; Guskey, 1986) has shown that, in order to be effective, teacher learning programmes should be active and practice-oriented (Clarke & Hollingsworth, 2002), and meaning- fully situated in teachers’ classrooms (Putnam & Borko, 2000). The experience of implementing new teaching practices changes teachers’ knowledge and skills when they experience that these yield better learning results and lead to pupils’ appreciation (Guskey, 1986, 2002). Reflection on the personal activities in the classroom can be considered as essential for teacher change. From the above it follows that we will take teachers’ educational practice as a starting point for their development. This study focuses on the continuous and long-lasting profes- sional development of mathematics teachers. We have chosen to use a strategy in which teachers collaborate in a network of colleagues, where the network meetings act as a sounding board (see Stiles, Mundry, Loucks-Horsley, Hewson, & Love, 2009). In network meetings they further improve and evaluate an earlier developed and implemented teaching design in the field of statistics for 7th grade pupils. The focus of this teaching design is on inquiry-based student work, aimed at students designing, performing and reporting statistical research. Through the network meetings teachers are introduced to the pedagogy of inquiry-based teaching. Our hypothesis is that the discussing of teachers’ experiences in the network meetings, their design of the lessons and their reflections lead to their development of practical knowledge (see also Darling-Hammond & McLaughlin, 1995; Meijer, 1999; Verloop, Van Driel & Meijer, 2001). We will use the Interconnected model of Professional Growth of Clarke and Hollingsworth (2002) as a means to describe the process of professional development (see also Anderson & Moore, 2006; De Jong, Van Driel & Verloop, 2005) and study teacher change. * Corresponding author. PO Box 800, 9700 AV Groningen, The Netherlands. Tel.: þ31 0 50 363 66 05; fax: þ31 0 50 363 66 14. E-mail addresses: info-uocg@rug.nl, m.g.witterholt@rug.nl (M. Witterholt). Contents lists available at SciVerse ScienceDirect Teaching and Teacher Education journal homepage: www.elsevier.com/locate/tate 0742-051X/$ e see front matter Ó 2012 Elsevier Ltd. All rights reserved. doi:10.1016/j.tate.2012.01.003 Teaching and Teacher Education 28 (2012) 661e674