A well-known ancient Chinese saying, "Building strong nations with good teachers," implies that quality education is the foundation of a nation's competitiveness and good teachers are the cornerstone of quality education. In recognizing the critical role that teachers and their teaching play in student learning conditions, the Teaching and Learning International Survey (TALIS) selected teachers' professional characteristics and pedagogical beliefs and practices as key policy areas for study in each of its three cycles (Organisation for Economic Co-operation and Development [OECD], 2009, 2014, 2019). Issues related to good teachers have become a key focus for education researchers, covering areas such as teaching, teacher education, and teacher professional development.  

Besides "good teacher" (Marom, 2018), diverse terms have been constructed to describe those who do a great job in teaching, such as "highly effective teacher" (Koutrouba, 2012; OECD, 2005; Swain et al., 2019), "expert teacher" (Goodwyn, 2017), "excellent teacher" (Hinz et al., 2019), and "outstanding teacher" (Chowdhary, 2023). Individuals who meet the requirements or standards of a good teacher are acknowledged and even rewarded in order to become a role model for other teacher colleagues and enhance the public's understanding of what good teachers do are critical for educational development in many countries, for examples, the Advanced Skills Teachers in England (Fuller, 2017) and Australia (Francis-Brophy, 2017), the Highly Accomplished Teacher in U.S. (Goodwyn, 2017), the Superfine Teacher in China (Wang & Cai, 2005), and the National Excellent Teacher Award in Taiwan (Wang, 1986).

However, what makes a good teacher has lacked a consensus among the public, even the professional, because of the socially constructed and culturally embedded concept of good teachers. Gudmundsdottir and Saabar (1991) used root metaphors to describe good teaching in different cultures, such as supermen in England, caregivers and interpreters of texts in Norway, skilled performers in the U.S., creators of a nation in Israel, and virtuosos in China. In Taiwan, a good teacher of the 21st century is a lifelong learner with educational love, professional competency, and future competency (Ministry of Education, n.d.).

Despite the multiple conceptions and descriptions of good teachers, a comparative study of policies aimed at improving teacher quality in 10 countries found that the key characteristics of high-quality teachers included commitment, love of children, mastery of subject didactics, and multiple models of teaching, the ability to collaborate with other teachers, and a capacity for reflection (Hopkins & Stern, 1996). From a sociobiological perspective, good teachers should possess adaptive expertise because teaching is a loosely structured profession with high unpredictability and variability (Goodwyn, 2017). They have the professional knowledge to solve real-world problems, further generating teaching theories. They also self-monitor and engage in deliberated practice when implementing their teaching practices. In Anderson and Taner's (2023) metasummary of 106 empirical studies, the good teacher prototype is reflective and critical, having well-developed pedagogical content knowledge and knowledge about learners, maintaining flexibility and strong interpersonal relationships in the classroom.

Because the conception of good teachers is socially constructed, many related empirical studies followed the qualitative research tradition, preferring the in-depth and whole contextual inquiry of specific cases. The rise in qualitative research studies on good teachers results in the need for knowledge aggregation. This study aims to synthesize qualitative research evidence on good teachers to understand the phenomenon of good teachers in Taiwan comprehensively.

Synthesis of qualitative evidence seeks to synthesize or amalgamate individual qualitative reports that relate to a specific topic or focus to arrive at a new or enhanced understanding of the phenomenon under study (Paterson, 2012). The approaches to synthesizing qualitative studies may incline toward descriptive or interpretive. A more descriptive approach leans on summarizing the findings of primary studies into a general description of a topic (Timulak & Creaner, 2023), while a more interpretive approach constructs new interpretations and generates new theories about a topic (Saini & Shlonsky, 2012). The synthesis approach used in this study is Timulak and Creaner’s generic descriptive-interpretive approach to qualitative meta-analysis, which can be used in a way that may oscillate between applying a more descriptive approach or a more interpretive approach and the researcher’s personal, professional, and theoretical background plays a crucial role in the synthesis process. After formulating the research questions that focus on good teachers, retrieving studies that focused on topics related to good teachers, inviting K-12 school teachers in Taiwan as research participants, using at least one of qualitative research approaches or mixed-methods research with an emphasis on qualitative data, contained data in the form of thick descriptions, and published or accomplished before July 31, 2024, in English or traditional Chinese was conducted. One hundred and seventeen studies were retrieved and met the inclusion and exclusion criteria. Of those studies, 55 (47.0%) were in elementary schools, 24 (20.0%) in junior high schools, 15 (12.8%) in kindergartens, and 11 (9.4%) in high schools. Nine studies covered multiple educational levels, while three (2.6%) did not specify a grade level. The CASP Qualitative Studies Checklist (Critical Appraisal Skills Programme [CASP], 2018) was used to know how the quality of primary studies affects research findings, which did not affect inclusion or exclusion decisions. Following the suggestions by Timulak and Creaner (2023), the data analysis procedure is flexible and iterative, including organizing the data into meaning units, forming domains of investigation from research questions, assigning all meaning units into domains of investigation, generating metacategories, and situating the interpretive framework of the researchers of primary and the meta-analyst. In addition, memoing was used in the data collection and analysis process. A preliminary meta-construction of the phenomena of good teachers identifies four metacategories related to the identification, professional qualities, and impacts of good teachers, along with influential factors.

How to identify good teachers has lacked consensus so far. One way is to focus on those reward winners, such as the National Excellent Teacher Award. However, most primary studies set their criteria for good teachers based on multiple criteria, typically including years of teaching experience, professional teaching performance, recommendations from others, and awards received. The knowledge base and reflection are the cognitive aspects of professional qualities among good teachers. The knowledge base of good teachers aligns with Shulman's (1987) classification of teacher knowledge, with educational purposes, values, and beliefs as a core linking other categories of knowledge. Reflection is a catalyst for transforming the accumulated or newly learned knowledge into effective and innovative teaching, with technical reflection occurring most frequently. Effective teaching is one of the most crucial components of good teachers' pedagogical practices, for example, selecting diverse teaching methods, clearly presenting teaching materials, and increasing student learning time. Continuous professional development is another essential component, such as dialogue and observation exchanges, self-learning, participating in training activities, pursuing degrees, and joining professional organizations. Of the external factors influencing the making of good teachers, the schools' atmosphere, culture, and physical environment impact good teachers' effective teaching and innovative teaching. In contrast, collegial interactions influence their continuous professional development. Regarding the internal influential factors, good teachers' growth and work experience significantly impact their professional qualities. These personal experiences need to be transformed through reflection, integrated into their knowledge base and subsequently manifested in the pedagogical practices of good teachers. The synthesis's findings on the teaching effectiveness of good teachers are limited, particularly regarding student academic achievement. However, good teachers positively influence students' self-confidence, cooperative skills, and learning attitudes and interests. Good teachers also affect the professional development of their colleagues, change the school atmosphere, and even impact the community, demonstrating their acts as teacher leaders.

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