This is my final editorial as Editor-in-Chief of the Journal of Mathematics Education (JMTE). Alongside the editorial team, our objective has been to contribute to the field of mathematics education by evaluating and publishing papers that provide new insights into phenomena in mathematics teacher education related to mathematics teaching and student learning. I am pleased to hand over this role to my colleague, Professor Alison Castro Superfine, who has served as an Associate Editor of JMTE during my term. Her research in mathematics teacher education, with a distinct focus on the teacher, the teacher educator, and mathematics knowledge, positions her well to lead the Journal and pave the way for new directions.

JMTE has continued to maintain its position as one of the leading journals in the field of mathematics education. The number of submissions received since the beginning of my term has doubled, indicating a growing interest among researchers to publish their work in JMTE. The majority of published research originates from the USA, with contributions also coming from European countries, Canada, and Australia. In an effort to encourage submissions and publications from underrepresented countries, JMTE established an Equity, Diversity, and Inclusion Committee in 2022. This committee is composed of volunteers from the Editorial Board, and its purpose is to promote equity, diversity, and inclusion in the research published in JMTE. (For more details, refer to Brodie's editorial in 2023.)

Upon reviewing the papers published in JMTE, a diverse range of topics has emerged. These include the exploration of teacher identity, knowledge beliefs, and the challenges faced by teachers in their daily instructional practices, implementation of innovations, and collaboration within teacher communities. Additionally, there is a focus on supporting teachers to balance ambitious teaching goals with the diverse needs of their students, emphasizing equity in education. Teacher decision-making has gained increasing attention, with a broadening interest in teacher noticing that extends beyond observing student thinking through video representations of practice. The studies predominantly involve prospective and practicing teachers, with some consideration given to mathematics teacher educators, coaches, and facilitators. While qualitative research prevails, cognitive perspectives dominate the theoretical framework, though a few studies adopt socio-cultural perspectives. Notably, there appears to be a small number of studies concentrating on “innovative” teacher education approaches and their impact on professional learning. Instead, more attention is directed toward understanding mathematics teachers within the context of their daily practice. The current issue's papers align with these observations, delving into various themes and issues that are integral to our field. There is a discernible shift toward addressing more complex phenomena related to mathematics teaching and teacher education. Three of the five papers in this issue center around the tensions experienced by teachers during the design and enactment of lessons. Two papers specifically emphasize cognitive and mathematical activities, reflecting an increased interest in understanding the intricacies of these aspects. The theoretical and methodological perspectives presented in these papers aim to tackle complex research questions, signaling a commitment to advancing our understanding of the multifaceted nature of mathematics teaching and teacher education.

Larsen, Østergaard, and Rasmussen address a longstanding issue in our field—the relationship between research and practice. They investigate whether development projects, widely central in many countries, have tangible impacts on mathematics teaching in classrooms. Employing a socio-cultural perspective, the authors utilize Activity Theory to contrast the activity system of a professional development (PD) project with that of the classrooms led by two experienced mathematics teachers playing a pivotal role in supporting professional learning. Applying the notion of expansive learning and leveraging Engestrom's characterization of contradictions within and across activity systems, the authors pinpoint contradictions within two large-scale PD projects in Denmark. These contradictions significantly influence the trajectory and outcomes of the projects, yielding outcomes in classroom mathematics teaching that fall short of the intended goals. Unveiling these contradictions in PD projects serves as a means of addressing them, fostering changes in mathematics teaching and learning. Larsen et al.'s study offers a critical examination of the PD projects, shedding light on the reasons behind their failure to meet designers' expectations and desires. This approach aligns with the broader exploration of PD programs that encounter challenges, as seen in the work featured in the current special issue of the Journal edited by Karsenty and Brodie (2023). This collective effort aims to scrutinize unsuccessful PD initiatives and uncover the underlying reasons, contributing valuable insights into the field.

Temizer's study adopts a cognitive approach to examine the reasoning of elementary prospective teachers (PTs) when dealing with ratios across a series of problems, with a specific focus on a step problem discussed in the paper. While reasoning with ratios among students has been extensively studied, the author extends this research to probe into PTs’ reasoning, emphasizing two primary strategies: the distributive partitioning operation and the multiplicative comparison of quantities. Conducting a constructivist teaching experiment involving two pairs of PTs, the author presents evidence that PTs encountered challenges, particularly in grasping multiplicative comparisons. Additionally, the study suggests that the representations and diagrams of the problem played a significant role in shaping PTs’ reasoning with ratios within the experimental context. The implications of this research for elementary teacher education are important. The findings offer teacher educators a deeper insight into the mathematical processes inherent in solving proportional tasks. While this perspective may not align with the mainstream research in mathematics teacher education, it underscores the importance of focusing on mathematics and how teachers construct their understanding of it.

Zbiek, Peters, Galluzzo, and White explore teachers' experiences with Mathematical Modeling (MM) and its instruction. Employing transformative learning theory and a retrospective research method, they identify the triggers and dilemmas encountered by teachers throughout their professional journeys that facilitated their learning of both practicing and teaching MM. The researchers utilize event history calendars, critical incident descriptions, and interviews with five experienced secondary mathematics teachers involved in MM instruction. The resulting learning trajectory encompasses five interconnected knowledge schemes related to MM: mathematics, social aspects, real-world context, students' thinking, and curriculum. These schemes, though not linear, demonstrate interrelatedness, with each linked to various triggers and dilemmas that prompted learning. Triggers surfaced during teachers' engagement in professional learning settings such as courses, conferences, and workshops, as well as during the design and implementation of daily teaching, and through interactions with colleagues and other educators. This study contributes to the ongoing effort in our field to comprehend professional learning over extended periods while recognizing learning as a complex process.

The paper by Lilly, Bieda, and Youngs presents a study on the lesson planning practices and challenges encountered by seven early career primary school teachers across four different school districts in the US, examining how they handle these challenges. The authors aim to identify differences between the lesson planning practices of teachers demonstrating high-quality instruction (HTM) and low-quality instruction (LTM), as characterized by the TRU Math protocol developed by Schoenfeld et al. (2014). Four HTM teachers and three LTM teachers are interviewed about their mathematics planning practices, use of curriculum resources, and the challenges they face. The analysis of the interviews is conducted with a focus on how teachers handle five persistent challenges in teaching, drawn from the literature review: curriculum, student participation, student thinking, managing student behavior, and teachers' own needs. The results reveal distinctions in the lesson planning practices of HTM and LTM teachers concerning these challenges. HTMs, in comparison to LTMs, are more inclined to: (a) consider specific students' learning needs, (b) address challenges independently rather than seeking support from colleagues, (c) reflect on prior teaching experiences and integrate them, and (d) creatively mediate curriculum resources while balancing multiple professional obligations to the mathematics discipline, students, and institutions. The study underscores that early career teachers encounter various challenges, and their experiences and approaches in handling these challenges differ. Recognizing and addressing these challenges in mathematics teacher education and during the mentoring process for novice teachers is crucial to meeting the diverse needs of teachers.

Alvidrez, Louie, and Tchoshanov investigate how secondary school mathematics teachers frame both student and their own mistakes. Specifically, they explore how teachers conceptualize mistakes in their teaching and analyze the teaching strategies associated with each framing. The study, situated in the US–Mexico border region, focuses on three teachers with distinct attitudes toward errors, as indicated by their responses in a questionnaire. The researchers identify two types of frames: epistemological frames, which categorize errors as resources or deficiencies, and positional frames, which distinguish between students capable or incapable of handling errors. The investigation incorporates classroom observations and interviews with these teachers, connecting their epistemological and positional frames to instructional practices and strategies. Taking a sociocultural perspective, the study highlights how teachers' responses to students' errors are contextual and reveal variations in how even the same teacher addresses errors using competing frames. This understanding of frames moves beyond simplistic dichotomies of good and bad handling of errors, emphasizing the complexity of the phenomenon, which involves both cognitive and affective dimensions. Teachers who view errors as resources tend to employ strategies that leverage errors as learning tools, emphasizing understanding over correction. Conversely, those who perceive errors as deficiencies often prioritize covering, correcting, or penalizing them. In terms of positional frames, teachers who see students as capable engage them individually or collectively to analyze and address mistakes. On the other hand, teachers who view students as incapable may skip mistakes or guide students in correcting errors. However, these relationships are not consistently observed across all teachers, and variations may be attributed to affective or social considerations. The study contributes valuable insights into the conflicting frames present in teachers' practices, challenging existing research assumptions about the consistency between teachers' epistemological beliefs about errors. Additionally, it provides mathematics teacher educators with tools to help teachers contemplate the significance of communicating errors in the classroom.

Concluding this editorial, I extend my sincere appreciation to numerous colleagues for their contributions as associate and guest editors, members of the editorial board, and reviewers for JMTE during my term as Editor-in-Chief. I thank the current and past associate editors for their collaboration, dedication, responsibility, and scholarly expertise in advancing research quality in the realm of mathematics teacher education. Presently, the associate editors are Alison Castro Superfine, Karin Brodie, Salvador Llinares, and Takeshi Miyakawa, while Kim Beswick, Gwendolyn Lloyd, Jeppe Skott, and Uwe Gellert have been associate editors with whom I collaborated in the past. I also thank  Karin Brodie and Ronnie Karsenty, who served as guest editors for the Special Issue titled “Researching 'What went wrong? Learning from less successful professional development for mathematics teachers,” published in October 2023 in JMTE. Additionally, I thank the members of the editorial board and the numerous reviewers, as their dedicated efforts are indispensable for the entire publishing process in JMTE. It is important to highlight that all these individuals contribute on a voluntary basis, serving the international community in mathematics education with the primary goal of advancing research in the field of mathematics teacher education. Lastly, I would like to thank the staff at Springer, with whom I have closely collaborated over the past six years. Their support has been invaluable in facilitating the successful functioning of JMTE.