Globally, curriculum reforms spotlight teacher agency as pivotal to educational change, yet how it is dynamically enacted in everyday practice and over time remains underexplored. A persistent puzzle emerges: within the same reform context, why do some teachers actively innovate and adapt their teaching, while others respond passively or revert to routines? Such divergence points to teacher agency as situated action—achieved through ongoing interactions with resources, constraints, and demands embedded in working environments. Understanding how agency is achieved and evolves is crucial for supporting teachers as transformative agents in curriculum reform.

This study addresses this issue by examining how high school teachers in Taiwan exercise their agency amid the implementation of the Twelve-Year Basic Education Curriculum Guidelines, a reform that emphasizes student-centered, holistic education and poses substantial challenges to teachers’ professional practice. Beyond subject knowledge and pedagogical skills, the reform requires teachers to navigate new expectations for inquiry-based learning, interdisciplinary integration, and reflective practice. By adopting a multiple-case study approach to explore agency-in-practice within this major policy shift, the study contributes to implementation-oriented scholarship and offers empirically grounded insights into how teacher agency is differentially enacted under shared structural conditions.

Scholars across different disciplines have yet to reach a consensus on the definition and meaning of agency. The concept is frequently conflated with other notions such as motivation, psychological traits, self-direction, resilience, rational choice, selfhood, will, purposiveness, intentionality, initiative, freedom, and creativity—terms that often overlap or even conflict—and is sometimes merely regarded as part of unexplained statistical variation (Hitlin & Johnson, 2015; Emirbayer & Mische, 1998).

This conceptual ambiguity has led to a lack of analytical depth, preventing teacher agency from being recognized as an independent analytical category. Consequently, much research offers only static typologies (“snapshots”) to categorize teachers’ behavioral or emotional tendencies in responding to educational change (e.g., Kang et al., 2022; Tinn, 2024; Pan et al., 2020), failing to capture agency’s fluid, processual nature as constructed through reform engagement (Kang et al., 2022; Robinson, 2012). A shift toward longitudinal, process-oriented perspectives is thus needed (Eteläpelto et al., 2013; Tao & Gao, 2017).

The ecological approach toward teacher agency (Priestley, Biesta, & Robinson, 2015a) addresses these gaps. It transcends the personal-trait versus structural-dualism debate, conceptualizing agency as an emergent phenomenon “achieved” through the interplay of personal capacities and the resources, affordances, and constraints of the action environment (Priestley et al., 2015a). This approach illuminates the core tension teachers face: between performative policies that constrain autonomy (Ball, 2003; Lasky, 2005) and reform demands for critical, innovative professionalism (Schleicher, 2016). In practice, this tension is often worsened by a various of pressures—from policy mandates and accountability to school culture and managerial issues—that can force teachers into compliance, thereby weakening their professional judgment, creativity, and sense of value (Chen, 2000; Richardson & Placier, 2001). Recent work further emphasizes teachers’ subjective perception and exploitation of their professional space (Oolbekkink-Marchand, 2017) and their responses to "affordances" within teaching environments (Aspbury-Miyanishi, 2022). In a crucial refinement, Aspbury-Miyanishi (2022) argues that the core of teacher agency lies not merely in willful action, but in the recognition of affordances. This shifts the analytical focus from labeling “agentic teachers” to examining “moments of agentic practice” within the flow of situated interactions.

Building on this framework, this multiple-case study aims to explore how teacher agency is manifested, developed, enacted, and shaped by ecological conditions. Specifically, this study expected to answer the following questions: (1) How does teacher agency develop and manifest dynamically throughout engagement with curriculum innovation? (2) What ecological conditions (resources, constraints, affordances) enable or constrain its achievement?

To investigate how high school teachers exercise agency amid ongoing curriculum reform, this study adopted a multiple-case study approach with a longitudinal and situated design. Grounded in the ecological approach toward teacher agency, this design enabled examining how teacher agency is dynamically achieved through the interplay of individual capacities and contextual conditions over time. The use of multiple cases further allows cross-case comparison to identify both shared logics and differentiated enactments of teacher agency across educational settings. Six in-service high school teachers were purposefully selected to represent diverse subject backgrounds, school contexts, and professional trajectories. Participants taught across science, humanities, languages, and the arts, with experience ranging from 10 to over 20 years. Three were senior full-time teachers, while the others had been contract teachers, introducing professional uncertainty relevant to the enactment of agency. All participants had completed a teacher education program emphasizing inquiry-based learning, interdisciplinary integration, and reflective practice, and aligning with the new curriculum guidelines implemented in Taiwan and providing a shared reference point for analysis. Data collection occurred between March 2022 and May 2025. Multiple sources were gathered to capture both practices and reflective accounts, including semi-structured interviews, classroom observations, and document analysis. Each teacher participated in three to five interviews, typically lasting one hour, with some extending to two hours; brief interviews conducted before or after lessons were supplementary. Classroom observations were conducted at least once for each teacher, covering two consecutive class periods and focusing on instructional decision-making and teacher–student interactions. Document data included school-level materials (e.g., school profiles, visions, curriculum maps), classroom artifacts (e.g., lesson plans, teaching materials, assessments), and teacher’s biographies or reflective writings. In the later phase, the storyline method (Oolbekkink-Marchand et al., 2017) was incorporated specifically as an essential tool to support retrospective reflection on teachers’ professional experiences and perceived autonomy over time. Teachers mapped their perceived and enacted professional space along a timeline of teaching experiences, using a scaled vertical axis to indicate levels of professional autonomy. This method enabled the visualization of temporal changes and supported analysis of how agency developed across different institutional and career stages. Data analysis involved iterative, inductive thematic analysis by the researcher. Within-case analyses were followed by cross-case comparisons to identify shared dynamics and divergent trajectories of teacher agency. Ethical considerations included obtaining informed consent and protecting participant anonymity through pseudonyms. Trustworthiness was enhanced through data triangulation, prolonged engagement, and member checking.

This study reveals teacher agency as a dynamically emergent process shaped through the continuous interaction between individuals and their multi-layered environments. Teachers' professional practices thus involve continual calibration within contexts of coexisting constraints and possibilities, representing agentic choices in response to specific conditions. The key findings generated from this study are: (1) Three distinct developmental trajectories were identified, demonstrating non-linear pathways: “Dynamic adjustment”, characterized by continuous adjustments and efforts in balancing multiple tensions; “Grounded practice”, marked by the accumulation of teaching experience and deep reflection on experiential knowledge; and “Sound expansion”, where teachers proactively broaden their influence through innovation and collegial engagement. This most advanced trajectory reflects what might be termed an “evolving self” (Kegan, 1979), wherein professional agency becomes deeply aligned with and directed by a teacher’s core values and self-expectations. (2) Teacher agency development follows cyclical fluctuations of “struggling in downturns” and “expanding during peaks.” The downturn phase is characterized by teachers navigating four structural pressures that constrict professional space: an exam-oriented culture prioritizing advancement, disparities in students’ foundational competencies, excessive administrative burdens, and socio-emotional expectations from parents and society. Conversely, the peak expansion phase emerges at the convergence of three enabling conditions: meaningful catalysts (e.g., a sense of mission ignited by student needs); structural support (e.g., institutional openness like curriculum deregulation, and professional empowerment resources); and interactive praxis (e.g., collaborative dynamics generated through professional learning communities). In conclusion, the ecological approach effectively captures the dynamic emergence of teacher agency, moving beyond the individual-structure dichotomy. It reconceptualizes agency as a temporally embedded and contextually emergent process, underscoring the need to foster supportive professional ecosystems that enable collaborative experimentation as a lever for sustainable change.

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