Workplace conditions created by principals for their teachers’ professional development in Vietnam

ABSTRACT Teacher professional development (TPD) plays a significant role in better school improvement and student achievements. Research on TPD shows that favorable workplace conditions greatly enhance teachers’ teaching knowledge and practice. This research was conducted to find out what workplace conditions principals had created to promote TPD in four schools in a province in Vietnam. The study utilizes multiple-site case study design relating to principal leadership and TPD in those schools. The four key workplace conditions were identified in this study including collaboration, teacher empowerment, supervision and evaluation, and teachers’ motivational strategies. Based on the findings, the study offers implications for both research and practice on principal leadership for TPD within and beyond the Vietnamese context.


Introduction
One of the key conclusions drawn from the sustainable education reform studies over the last two decades is the vital significance of teacher professional development (TPD) (Clement & Vandenberghe, 2001;Darling-Hammond & Richardson, 2009;Qian, Walker, & Yang, 2017;Timperley, 2011;Vescio, Ross, & Adams, 2008). The first formal studies on TPD focused mainly on the roles of pre-service education and in-service workshops/seminars in TPD (Joyce, 1988). However, TPD has been a process initiated during pre-service teacher education time and continues through job-embedded, collaborative, coherent and reflective professional activities, for the last few decades (Hallinger, Piyaman, & Viseshsiri, 2017;Kwakman, 2003;Lieberman & Pointer Mace, 2008;Opfer & Pedder, 2011;Poekert, 2012;Timperley, 2011;Webster-Wright, 2009). This led researchers' attention to understanding how workplace conditions enhance teachers' participation in productive and effective learning during their teaching careers (Geijsel, Sleegers, Stoel, & Krüger, 2009;He & Ho, 2017;Qian et al., 2017;Sleegers, Thoonen, Oort, & Peetsma, 2014;Youngs & King, 2002). A central theme in these studies as well as in the research literature is the role of school leaders in creating favorable working conditions for TPD.
Recent studies on TPD have paid more attention to developing countries where the quality and scope of pre-service teacher education need to be reformed in response to educational changes (Hairon & Dimmock, 2012;Hallinger et al., 2017;Lai, Li, & Gong, 2016;Qian et al., 2016;Somprach, Tang, & Popoonsak, 2016;Wang, 2016). In Vietnam, the Communist Party and the government have recognized that the success of education reforms depends mainly on the ability of principals and teachers to learn new and innovative knowledge, skills and attitudes on-the-job (The Communist Party of Vietnam [CPV], 2012;London, 2010;Mai, 2007;Mau, 1998;Ministry of Education and Training [MOET], 2012;Nguyen 2003Nguyen , 2012Tran, Hallinger, & Truong, 2018). In order to find out the impacts of principal leadership on their TPD, this research specifically addressed the following question, 'What workplace conditions do the principals in four schools in Hong Lam province create to promote their teachers' professional development?'. By addressing this question, our aim is to explore whether the principals used practices highlighted or suggested by the literature have impact on TPD.
This study used a qualitative case study of leadership and TPD in four schools. Our analysis aimed at identifying the favorable working conditions for teachers created by their principals to promte TPD in their schools in Hong Lam province, Vietnam. In this way, the study highlights the cultural dimensions of principal support, which are specific to the educational and sociocultural context of Vietnam. This approach is congruent with Bajund's advocacy for cultural aspects of leadership unique to each specific education system.

Vietnamese context and literature review
We believe that it would be impossible to understand how principals promote TPD in the society of Vietnam without taking the influences of the social, economic, educational and cultural context into consideration. In this section, cultural and educational context of Vietnam will be discussed. Then, we will discuss the roles of principals in creating favorable conditions for teachers' professional learning.

Social and cultural context of Vietnam
The Vietnamese culture has been influenced by a blend of different indigenous ethnic groups, Chinese Confucianism and Taoism, Buddhism, Communism, and Western cultures including French and American ones (Borton, 2000;Dalton, Hac, Nghi, & Ong, 2001;Nguyen, 2013Nguyen, , 2016Vasavakul, 2019). For example, although social relationships among Vietnamese are strongly hierarchical and collectivist as a result of Confucianism influence (Borton, 2000;Duiker, 1995;Jamieson, 1993;Nguyen, 2013), Communism has reshaped these traditional Confucian and Taoism values into a unique Vietnamese form (Borton, 2000;Dalton et al., 2001;Nguyen, 2016). Moreover, since Vietnam started its open-door policy and integrated into the world in 1986, Vietnamese culture has been also influenced more by Western values such as individualism and equality in social relations (Dalton et al., 2001;Nguyen, 2016;Vasavakul, 2019).
However, hierarchy continues to be a normative feature of social relations in Vietnamese society. Elders or seniors expect respect from younger people or those recognized as having lower social rank or social status (Dalton et al., 2001;Lan, 2002;Vasavakul, 2019). Respect is expressed in several forms such as listening attentively to, or not disobeying your seniors' advice and suggestions, or in the ways we address one another in communication. An obvious indication of respect involves addressing one another in communication by using various pronouns. Such pronouns reflect the order, age and status of addressers and addressees in the family, community, or society (Truong & Hallinger, 2017;Vasavakul, 2019). In schools, juniors whether students, teachers or principals typically wait for seniors to express their opinion first in order to avoid causing conflict or loss of face (Borton, 2000;Dalton et al., 2001;Hallinger & Truong, 2014;Jamieson, 1993;Tran et al., 2018;Truong & Hallinger, 2017;Truong, Hallinger, & Sanga, 2016;Vasavakul, 2019).
These values and norms are evident in the education system. Vietnamese teachers have been considered among the most important people not only in education but also in wider society (Hoang, 2002;Huynh, 2002;Hallinger & Truong, 2014;Lan, 2002). Due to the influence of Confucianism, 'the teacher occupies a central place in the student's life and is revered for the wisdom he provides' (Ozmon & Craver, 2008, p. 117). Thus, the role of both teachers and principals must be interpreted in light of the context of culture and education in Vietnam (Huynh, 2002;Truong & Hallinger, 2017).

Education in Vietnam
Vietnam has carried out the doi moi (reform) policy since 1986 and has focused on the socio-economic development of Vietnam (Duggan, 2001;Hac, 1998;MOET, 2012;Nguyen, 2002). Education is always considered to play a vital part in the doi moi process, the current education system is, nevertheless, ill-equipped regarding the quality of curriculum, facilities, teaching methods and teaching staff (Duc, 2008;London, 2011;Nguyen, 2002;Tran et al., 2018;Truong & Hallinger, 2017). Addressing these challenges has been the goal of educational reforms since the beginning of the millennium (Duc, 2008;London, 2011).
In Vietnam, the MOET is responsible for organizing the functional responsibilities for education including curriculum, teacher qualifications, educational standards and testing. However, it is noted that in Vietnam, authority over many of these issues is shared with the Communist Party committees at the national, provincial, district and school levels Tran et al., 2018). This shared authority division, both at the educational system and school levels, reinforces the multiple purposes of education in Vietnam: political/moral qualities (duc) and professional knowledge (tai) (Doan, 2005;London, 2011). Duc refers to virtues or moral qualities and incorporates values that arise from Confucianism, Taoism and Communism. Duc can, for example, refer to traditional cultural values such as filial piety (hieu), loyalty, respect for 'seniors' as well as to faithfulness to the values of the Communist Party (Dalton et al., 2001;Hoang, 2002;Huynh, 2002;Nguyen, 2002;Truong et al., 2016). A big distribution of the formal school curriculum in schools in Vietnam is allocated to political and moral education (Doan, 2005;Vasavakul, 2019). Tai refers to knowledge, skills, professional competence or ability (Mai, 2007;Vasavakul, 2019). When a Vietnamese refers to a 'tai teacher', it implies that the teacher masters profound professional knowledge and skillful teaching methods (Hamano, 2008;Mau, 1998;Nguyen, 2002;Tran et al., 2018).

The study
The qualitative, multi-site case study design was used for this study as we emphasized on understanding through looking closely at people's words, actions and records (Denzin & Lincoln, 2017;Maykut & Morehouse, 1994). In the following sub-sections, we describe the processes of site selection, data collection and data analysis.

Sample selection
This research took place in Hong Lam (pseudonym) Province in the center of Vietnam. Purposeful sampling was utilized in this study to select 'information-rich cases whose study will illuminate the questions under study' (Patton, 2015, p. 169). Four schools from four educational levels in different geographical locations in Hong Lam province were considered to gain high achievements by Hong Lam Provincial Department of Education and Training. Their characteristics were as follows: • School A: This primary school has 600 students in 15 classes from grades 1-5 in the city. Principal Mr. Hoang (pseudonym) leads 23 staff including a deputy principal. The School has been recognized for excellence in academic and moral achievements at the provincial level. Eighteen teachers hold three-year and four-year bachelor's degrees. The Principal has 15 years of experience as a principal including twelve years at this school. Before being appointed to this post, he had been a teacher for three years and deputy-principal for seven years. • School B: This lower-secondary school located in a rural area serving 950 students in grades 6-9. It has been recognized for excellence in academic achievement. There are 52 staff members including the principal and deputy principal. The principal, Ms. Le (pseudonym), has 10 years of experience as a principal. Thirty of the teaching staff have three-year or four year training degrees. • School C: This high school for gifted pupils (grades 10-12) has 600 pupils from all parts of the province. Approximately 100 percent of the 12th grade pupils pass the university entrance examination every year to get admission to different universities in Vietnam. There are around 50 staff members including the principal, Mr. Nguyen (pseudonym), and deputy-principals. There are 40 teachers of whom one holds a PhD degree, seven hold M.A degrees, the rest have four-year training diplomas (bachelors' degrees). • School D: A College of Vocational Training serving about 1,800 students in five departments. The College is led by a rector, Mr. Cao (pseudonym) and two deputy rectors. There are 120 teaching staff. According to the documents, the College has received many rewards from the provincial and MOET levels.

Data collection
The research data came from semi-structured interviews with the four principals, openended questionnaires from teachers, direct observation of professional development activities and related policy documents (Patton, 2015). Semi-structured interviews (Patton, 2015) were conducted with each of the four principals (See Appendix A). More specifically, each principal was interviewed for about 90 minutes in an office or staff room. These interviews aimed at gaining information about the principals' perspectives and their leadership practices, their roles and support as well as and teachers' professional learning activities in their schools. All the interviews were audio-recorded and later transcribed in Vietnamese. Only data extracts used as quotes in this paper were translated into English by an experienced lecturer in English and checked by the research team.In addition to the interviews with principals, teachers' perspectives were collected from an open-ended questionnaire that focused on teachers' needs and motivations as well as professional development practices used in their schools (See Appendix B). A total of 177 of 235 questionnaires distributed at teachers' meetings were returned (75% response rate). In order to gain further details and check on what had been reported in the interviews and questionnaires, we also observed TPD activities in the four schools over a three-month period. The TPD activities included bi-monthly meeting for peer learning in three schools and monthly meeting in the college. The lead author as the investigator-in-chief of the study made notes of each meeting, which were used as a source of data. These sources of data offered multiple perspectives and enabled the use of triangulation as a means of checking the credibility of different perceptions (Creswell, 2014;Denzin & Lincoln, 2017;Miles & Huberman, 1994;Patton, 2015).

Data analysis
In this multi-site case study, we employed 'within-case analysis' followed by 'cross-case analysis' (Miles & Huberman, 1994;Patton, 2015). Within-case analysis involved developing detailed write-ups for each school according to the foci of the research. Analytical procedures first involved coding data based on sources. First, we read the interview transcripts and teachers' responses to the questionnaire in order to form initial codes. Next, we related the codes to the notes of TPD activities made by the investigator-in-chief plus the policy documents. Finally, we organized the data by arranging it into a case record (or database) for each school (Patton, 2015).
In the cross-case analysis, we tried 'to build a general explanation that fit each of the individual cases, even though the cases vary in their details' (Yin, 2014, p. 112). During the process of data synthesis, we used open coding, axial coding and constant comparative method (Glaser & Strauss, 1965;Patton, 2015). We generated categories as we searched for patterns, commonalities and contradictions among four schools (Patton, 2015). For example, the category 'collaboration' was formed by a synthesis of all the codes emerging from interview data collected from each principal, including 'sharing ideas', 'cooperating', 'providing peer feedback', 'collegiality', 'open relationship', 'peer interaction', and 'collective work'. Other patterns underwent a similar process. The generated categories recognized the importance of taking account of both personal and contextual influences in shaping leadership practices and workplace conditions (e.g. see Belchetz & Leithwood, 2007;Clarke & O'Donoghue, 2017;Hallinger, 2016;Tran et al., 2018). For data analysis in this study, we decided to embrace findings with discussion. As such, each theme or category as one of the main findings was discussed in relation the literature. For example, the pattern 'collaboration' as one of the emergent theme in this study was discussed in relation to the established literature on collaboration for TPD. By this way, we could achieve the aim as to whether TPD practices in the previous studies on principal leadership were relevant to the Vietnamese context. More importantly, grounded in Bajunid's (1996) advocacy for cultural dimensions in principal leadership, this way of data analysis helps to foreground the cultural and social aspects of the Vietnamese context.

Results and discussion
This study data confirmed the use of both external and school-based TPD activities. External activities included degree upgrading courses offered by the MOET and universities, seminars, summer workshops, short courses, and district/provincial/national good teacher title competitions. School-based activities included class observations with feedback, observations of other teachers, weekly faculty meetings, mentoring, coaching, and self-study.
Cross-school analysis of TPD activities revealed that the four schools relied mainly on 'external activities'. However, the teachers generally found these external learning activities less directly relevant, of limited use, costly, and time-consuming. In contrast, inschool learning opportunities were generally perceived as more relevant, useful, and related to perceived needs of the teachers.
These data strongly supported the proposition that workplace conditions played a critical role in promoting the extent and nature of teacher participation in TPD activities (e.g. Clement & Vandenberghe, 2001;Rosenholtz, 1989;Sleegers et al., 2014). Data analysis yielded four workplace conditions to support TPD, created by the principals, including collaboration, teacher empowerment, supervision and evaluation and teachers' motivational strategies.
In this study we examined practices used by four Vietnamese principals to support the professional learning of teachers. Although our perspective on leadership and teacher learning was initially shaped by Western literature, the use of a qualitative research methodology allowed for an exploratory rather than a confirmatory approach to the literature. Thus, we inductively identified and described leadership practices within four broad leadership strategies. Our cross-school synthesis paid particular attention to how these practices reflected the educational and cultural context of Vietnam. In the next section, we will briefly discuss workplace conditions, created by the principals, to support TPD, interpret the findings, mention the limitations, and highlight implications for research and practice.

Collaboration
In TPD, collaboration means that teachers work together, building and sustaining relationships with colleagues, promoting improvement in instructional capacity by providing feedback, fostering reflection on teaching skills and developing new teaching techniques (Denton & Hasbrouck, 2009;Gumus et al., 2013;He & Ho, 2017;Heck & Hallinger, 2014). Collaboration was evident in all the four studied schools. It was clearly reflected in a number of strategies including observations, school or department-based seminars, mentoring, coaching and weekly professional meetings. The teachers were provided with opportunities to discuss with their colleagues professional issues for improvement and development in teachers' learning and teaching. Almost all the teachers said that they felt challenged by their colleagues. Teaching methods and problems were discussed frequently in meetings and seminars. Colleagues offered help in difficult situations. Staff said they could learn from one another during the meetings and seminars. Clement and Vandenberghe (2001, p. 45) argued this was effective when they said, '[C]ollegiality challenges teachers professionally because colleagues function for one another as a source of feedback, support and alternative ideas'. The teachers in these schools said they were eager to help one another to implement new learning or put new ideas into practice. This was similar to the pattern of successful teachers in Spillane's (1999) longitudinal study and in Heck and Hallinger's (2014) study.
Teachers' professional identity can also be developed through experiences of solidarity and collective work (Tonna & Shanks, 2017), a process through which teachers are made aware of how they can contribute to the growth of each other's professionalism, as in Tonna and Shank's study. Most interactions between the principals and their teachers were dominated by the creation of learning opportunities. Collaboration and collegiality were evident in informal activities including the exchange of ideas or stories between the principal and teachers during the breaks. These stories had the character of noncommittal small talk. Many teachers and their principals discussed the weather, politics, shows on T.V, or their families. Often these stories grew to a sharing of ideas with regard to the school. These interactions are similar to those described in Heck and Hallinger's (2014), Rosenholtz's (1989) and Spillane's (1999) study. They were seen more frequently in schools D, C, B, and A. In school A, Mr. Hoang participated actively and frequently in all strategies with his teachers and teachers valued this cooperation. The teachers also appreciated the fact that they could easily discuss educational issues, especially issues related closely to the educational reform with their principal. In general, they did not find it difficult to ask for help. According to the teachers, they could ask Mr. Hoang for feedback about their pedagogical activities and their interactions with their pupils. Sometimes, Mr. Hoang commented spontaneously on teachers' work.
Mr. Nguyen from School C and Ms. Le from School B did similar things, but to a lesser extent. These two principals mainly discussed teaching methods with their teachers. This was because there were more subjects in their schools. Because of the college size, Mr. Cao did not meet all teachers as often as the other principals. He collaborated more with heads of departments. However, beside meeting with his teachers in seminars and meetings, he tried to talk with his teachers informally by going down to the department hall, meeting with them at social activities, organized by the department or the college, and playing sports with them.In general, in the four schools, collaboration created opportunities for the teachers and principal to share their personal opinions and beliefs about teaching. At the same time, it left room for teachers to work independently (self-learning, mentoring and discussions). Collaboration is linked with norms and opportunities for continuous improvement and career-long learning that is significant for improving instructional capacity (Denton & Hasbrouck, 2009;Fullan, 2001;Gumus et al., 2013). All the four principals tried to encourage and promote interactions and cooperation mainly in professional development between teachers. The principals used reward and encouragement systems and regulations to supervise teachers.The literature indicates that collaboration in schools is on trusting, caring, and open relationships (Fullan, 2001(Fullan, , 2010Hallinger & Truong, 2014;Harris & Jones, 2019;Tran et al., 2018). One the one hand, these constituents of collaboration were evident in the four schools. One the other hand, collaboration in these schools shows two characteristics reflecting the socio-political landscape of Vietnam, namely the 'right relationship' originated from Confucianism (Borton, 2000;Ozmon & Craver, 2008;Tran et al., 2018;Truong, 2013) and 'the dominant political role of the Communist party' (Duiker, 1995;Vasavakul, 2019) In particular, age, status, experience, and even gender in the Vietnamese culture created an 'invisible' distance between the teachers and their principals and between teachers themselves. In general, collaboration for TPD as highlighted in the findings of this study manifests both the shared characteristics of the literature and the cultural dimensions of leadership in Vietnamese education.

Teacher empowerment
Overall, the teachers were empowered to some extent in the four schools. Teacher empowerment was evident in strategies such as seminars, weekly professional meetings, mentoring, peer coaching, and self-learning. Teachers were occasionally provided with an opportunity to be involved in decision-making and leadership roles. According to Melenyzer (1990, cited in Blasé & Blasé, 1994 when teachers assume responsibility for an involvement in the decision-making process, true empowerment leads to increased professionalism.
Teachers in school D had more chance to take a leadership role in their professional development than their counterparts in the other three schools. For example, teachers could state their opinions on the topic selection process for seminars at the college level. They were free to choose materials for their students. They played a leadership role when organizing seminars at the department level, in mentoring and in coaching. Mr. Cao stated, In my views, we created general policies. Teachers, based on those, take an active and creative role in generating new ideas and good ways to implement them. Sharing good ideas among teachers and reflection on their expertise are encouraged and appreciated" (DDI).
Teachers of this college could also choose the areas for self-learning they thought they needed to improve on. To a lesser extent, the teachers of the other schools experienced similar opportunities. They could take active roles in providing guidance and support to novice teachers as well as others. However, the principals were close to them and they participated in almost all areas of TPD. Thus, opportunities for empowerment for teachers were limited.Thus, Vietnamese teachers generally experienced some kind and extent of shared leadership and autonomy in their learning in the four schools. It may not have been as much autonomy, self-responsibility, and self-direction as their counterparts in Western schools might expect. Rather, teacher empowerment in the four schools focuses less on individual rights, discretion, and freedom and more on the commitments, obligations and duties that teachers feel toward each other, their students and the school. Based on these characteristics, we argue that teacher empowerment in these Vietnamese schools is also affected by the hierarchical structure (Borton, 2000;Tran et al., 2018;Vasavakul, 2019). Again, teacher empowerment has its own cultural dimensions in response to the culture and history of Vietnam.

Supervision and evaluation
Supervision and evaluation of teachers' professional growth were evident in all schools. The management board, mainly the principal, was in charge of this task. It was considered an integral part of teachers' professional development. The role of principals in the promotion of effective professional development is reinforced by Hallinger and Liu (2016) when they suggest that instructional supervision, often provided by the principal, helps teachers improve their instructional performance, motivate their professional development and carry out their curricular development as well.
Evaluation of teachers was frequently carried out in all four schools. At the end of a semester and an academic year, teachers were assessed. Assessment was based on similar procedures and criteria in each of the schools. Teachers were assessed in terms of 'duc' and 'tai' (Doan, 2005;Mau, 1998;Hamano, 2008;Nguyen, 2002). Teachers' 'duc' often included: their patriotism, socialism and beliefs in the leadership of the Party and government, their obedience toward laws, and regulations issued by the State and MOET, their enthusiastic participation in social activities organized by the school, their collaboration in work, their behaviors toward other colleagues and their students, and the respect and prestige gained from other staff and students. Teachers' 'tai' consisted of assessed observed lessons, results of scientific studies, writings for the Bulletin of Science and presentations, and contributions to seminars. Based on such criteria, teachers wrote their own self-evaluation reports and graded themselves as A (good), B (credit), C (pass), or D (not completing the assigned tasks). Then, in department meetings (in schools B, C, and D) and the whole staff meeting (school A), teachers took turns to present their own reports to get feedback from their colleagues and the principal (in schools A, B, C) or heads of departments (in school D). At these meetings, constructive criticism was encouraged by all the principals. At the end of the meeting, teachers were graded by other teachers anonymously. In school D, after that meeting, lists of teachers' grades were sent to the College's Education Council for final assessment and approval.
The principals and most teachers in the four schools considered this kind of evaluation necessary and effective for recognition of their achievements and improvement. Simultaneously, this provided teachers with a chance to look back at their strengths and weaknesses and the opportunity to develop their sense of responsibility. These seemed to be similar to Little's (2012) views when (s)he suggests that evaluation is necessary for teachers' continued professional development and that good and thorough self-evaluation should include seeking the perceptions of other knowledgeable colleagues. Other authors also noted the significance and positive effects of evaluation on teachers' enhancement and development (See, for example, Little, 2012;Somprach et al., 2016).In-class supervision, as termed by Glanz and Neville (1997), to assess in-service activities was evident in the four schools. It included observations, following discussions, and assessment of teachers' lessons during the academic year, especially on special occasions. What some teachers had learnt from workshops and seminars was shared with other teachers. Then, the new learning was applied to classes. Observations and discussions were encouraged. This cycle was considered by principals and teachers as crucial to the success of in-service training workshops and improvement of teachers. Follow-up activities depended on observations in the school. Ms. Le and especially Mr. Hoang frequently took part in observations and discussions. Mr. Nguyen had some involvement and Mr. Cao rarely did. Follow-up activities were carried out more frequently in schools A and B where the principals were more involved. According to Botello and Glasman (1999), where there are more follow-up activities, there is more likelihood of successful in-service training courses and workshops.
In conclusion, supervision in all the four schools appeared to focus less on instructions and more on assessment. As such, this way of supervision is not similar to models of effective supervision in other education systems, especially ones of Western countries. In the schools as research sites of the current research, supervision supportted teachers in adapting, adopting, and refining the instructional practices they were trying to implement in their classrooms. The primary purpose of supervision was illustrated in Mr. Cao's views: We supervise for good reasons. We want schools to be better, teachers to grow, and students to have academically and developmentally sound learning experiences; and we believe that supervision serves these and other worthy ends. But all the benefits that we seek can be obtained more easily and in enhanced ways in the natural course of events as teachers and students learn together in the school." (DDI).
According to Hairon and Dimmock (2012), the type of instructional supervision that is most likely to produce productive professional development is that of collaboration. The supervision in the four schools is tailored for the education context in Vietnam. As a result of this, supervision in these schools is not like the one employed in Western schools.

Motivational strategies
The teachers in the four schools were motivated to continuously update their knowledge and professionalism. The motivation system in these schools often included policies, regulations, rewards, recognition, and punishment. It appeared that the four principals used different motivational strategies to promote teachers' professional development.
In order to apply suitable motivational strategies to individual teachers with different needs, the principals were reported to have an understanding of their teachers. Generally, the principals understood almost all of their teachers' family situations. Family situations in Vietnam appear to have a great impact upon teaching and learning. For example, Vietnamese female teachers have to be involved in work and family as well. Because of an influence of Confucianism, they have to take responsibility for household chores. Thus, they have less time for self-learning than their male counterparts. The principals acknowledged the differences in teachers' needs, age, gender, and financial conditions when employing strategies of professional development. This was reflected in compulsory and optional strategies applied in schools. For example, observations, scientific studies, and self-learning were compulsory and degree upgrading was optional. All teachers valued these understandings. There were no indications of unfair considerations or teachers' dissatisfied attitudes toward their principal's acknowledgments of different needs in the interview or questionnaires. School reports and my observations confirmed these. These principals' actions seem to be consistent with what He and Ho (2017) suggests. They say that the use of suitable motivational strategies based on individuals' needs and work characteristics is very important to stimulate teachers to improve (Kwakman, 2003). Darling-Hammond andRichardson (2009) andFullan (2010) also argue that teachers' needs must be taken into consideration when employing teachers' professional development strategies.
Policies of rewards and punishment were used to implement and promote TPD in all four schools. Teachers with high achievements or good progress including successful completion of degree upgrading, attaining 'good teacher' titles, good grades for scientific studies, and so on, were recognized, appreciated, and awarded with money. These teachers were publicly appreciated and praised. According to Mr. Hoang, when a teacher completes a 'degree upgrading' course, at the staff's meeting, that graduate is awarded with 'a small gift as a kind of reward and recognition of his/her endeavor'. The value of such an incentive was explained: 'Although the reward is small because of the difficulty in finance, it is great encouragement for that teacher in front of his/her colleagues' (ALI). Teachers with 'good teacher' titles were recognized and awarded amounts of money in schools B, C, and D. Mr. Cao said that in his college, teachers with high achievements and grades were received more money than others on some occasions such as Vietnamese Teachers' Day and Lunar Year (Tet) Holidays. Teachers in schools A, B, and C were also awarded with money if their students passed the 'good student' competition at DETS or PETS levels. Thus, it is a fact that teachers normally wanted to teach the more able students. However, the principals tried to assign teachers to teach different classes. Teachers in the four schools with their scientific studies recognized at DETS or PETS levels were awarded with money as well. The higher the level was the more money and respect the teachers gained. These kinds of rewards seemed to make teachers competitive and they are not always encouraged in Western schools. London (2011) argues from the left that the sense of competitiveness partly prevents teachers from collaborating with their colleagues. Although the principals and teachers did not mention the sense of competitiveness in the interviews and questionnaires (they might not have realized or they would not have wanted to say about), we saw evidence of the sense of competitiveness amongst teachers in the four schools.
One kind of motivation that reflects cultural dimensions of Vietnamese style of leadership is 'reward of spirit'. This term was repeated in the principals' interviews and teachers' questionnaires. They said that the reward of a Vietnamese teacher can be good and wellbehaved students and that he/she is loved and respected by their colleagues and students' parents. This is very important for teachers. Thus, the principals said that they often reminded their teachers about the honor of the teaching profession in the Vietnamese society. Most teachers wrote that their professional development was mainly important to them because they could help improve their 'dear students' learning and achievements. This could result from an influence of Confucianism that teachers should be good and hold high respect in society (Hallinger & Truong, 2014;Huynh, 2002;Ozmon & Craver, 2008;Tran et al., 2018;Truong & Hallinger, 2017).Teachers in the four schools said their principals placed high expectations on them to improve their learning and teaching.
Mr. Hoang noted the 'school A pride' for teachers to strive more in learning and teaching. However, the principals realized that their teachers' salaries were not sufficient for their living, therefore their teachers could not put as much effort into teaching and learning as they might desire. Thus, rewards from the schools were often money. All four schools said that they lacked the finance for better encouragement and worthy rewards for their high achieving teachers. All four principals, living and working in a hierarchical society, were seen to use 'X' theory in some cases to motivate their teachers.
According to Borton (2000), Nguyen (2016), Tran et al. (2018), and Truong (2013), in Vietnamese culture, achievement goals are often described as being for the benefit of the group (e.g. family or organization or state). Mai (2007) also suggests that collective cultures emphasize achievement more in terms of benefits to the in-group. According to him/her, people in these cultures are often motivated to study because of a stronger emphasis placed by their family, organization, and society on education as a means to achieve wealth and status. Moreover, the sense of 'losing face' could motivate people to learn. This practice of motivating teachers is traced back to an established norm in Vietnamese society. That is, 'a small food given formally to a person in front of the whole villagers is considered more precious than a basket of food given informally to him/her in the house' still holds true in organizations including schools. The four principals seemed to understand these cultural aspects embedded in their teachers as Vietnamese in order to motivate their teachers more effectively. For example, the teachers were often praised and rewarded publicly.

Limitations of the study
Like other case study research, this study involved a limited and specific population of participants. Therefore, the findings of this research cannot be generalized to the larger population of Vietnamese schools and educators (Yin, 2014). In addition, it is possible that the information and perspectives shared with the researchers conveyed 'overly positive' assessments of modal practices in the schools. While this is a commonly noted threat to validity in qualitative research (Burns, 2000;Creswell, 2014), features of Vietnamese culture and Vietnamese context could have exaggerated this tendency in our study. More specifically, Vietnamese people behave in accordance with the norm of 'good things are revealed and bad things should be covered up (tốt khoe xấu che). Although our use of data triangulation, especially observations, tried to improve credibility and validity, we acknowledge this as a limitation of our study.
As in the findings of the current study, the level of schools played a role in the leadership practices used by the principals. In particular, the principals from primary and lower-secondary schools were more involved in TPD than the principals from upper secondary and vocational training schools. We did not discuss this aspect in detail due to the limitations of the study. As such, the role of school level in principal leadership should be a useful topic for future research on educational leadership in the sociocultural context of Vietnam.

Conclusion
The principal leadership strategies identified aimed at supporting TPD identified in this study echo themes that have been well discussed in Western nations. Nonetheless, it was obvious that the implementation of these strategies in typical schools in Vietnam had a different feature which reflected the influence of the political, cultural, and socioeconomic context of Vietnam. The findings offer support to the ideas of Belchetz and Leithwood (2007), Harris and Jones (2019) or Hallinger and Heck (2010) that a similar successful leadership practices are found in different countries. At the same time, they reinforce Bajunid's (1996) idea that these similar practices (e.g. empowerment, collaboration, supervision) may take on different patterns in different countries. This was evident in the current study and needs more qualitative studies that elaborate on and connect leadership and TPD practices to the contextual features of different countries (Belchetz & Leithwood, 2007;Clarke & O'Donoghue, 2017).
In this research article, we have periodically compared our findings in the four schools in Hong Lam province, Vietnam to the studies of leadership and TPD conducted in Western countries. Indeed, as noted above, we concluded that differences in these practices could be traced to differences in the educational and socio-cultural context. However, it should be noted that in recent years an increasingly rich literature centering on this topic has emerged in East Asia with the studies from Hong Kong He & Ho, 2017), China Qian & Walker, 2013;Qian et al., 2016), Thailand Somprach et al., 2016), and Singapore (Hairon & Dimmock, 2012). Future studies should assume the challenge of examining commonalities and differences in these processes within East Asian societies. This will not only offer policymakers, educational authorities and practitioners in the region insights into further development directions, but also contribute toward building a more diverse global literature in educational leadership and management as a whole (Bajunid, 1996;Clarke & O'Donoghue, 2017).
We focused explicitly on describing TPD practices and interpreting them through the political-cultural-social lens of the Vietnamese context. Nonetheless, if we compare Vietnam with findings reported from China and Singapore, the schools in Hong Lam province, Vietnam in particular and perhaps in Vietnam in general, lag these other East Asian countries on both the scope and quality of leadership and TPD. This would suggest that there remains a gap for further studies in the field in Vietnam.

Disclosure statement
No potential conflict of interest was reported by the authors.

Notes on contributors
Hai-Ngoc Tran, got an MA from Otago University, New Zealand, and is currently doing his PhD at Vietnam National Institute of Educational Sciences, Hanoi, Vietnam. He is a senior lecturer at Department of Foreign Languages, Ha Tinh University, Vietnam. His research interests include