Professional Life Phases of Teacher Educators: The Case of a Vietnam Institution

Teacher educators influence the quality of future teachers and teacher education programs. However, their professional life during their mid and late career has not been scrutinized considering their work experience, particularly in Vietnam. Hence, this qualitative study explores the professional life phases of eight Vietnamese teacher educators, whose experience ranged from 6 to 26 years. In-depth interviews were conducted and a lifeline chart was applied when possible. The constant comparative method was applied for cross-comparison between cases. The study results revealed four career phases, including Phase I—Adaptation and competency building (1–5 years of work experience), Phase II—Stabilization (6–10 years of work experience), Phase III—Prosperous engagement (11–20 years of work experience), and Phase IV—Calming down or winding up (21 or more years of work experience). The findings may help administrators tailor teacher educators’ professional development based on their experience and expertise. Plain Language Summary Exploring the Career Phases of Teacher Educators through a Grounded Theory Approach This study aims to encapsulate the portraits of the professional life phases of eight teacher educators in Vietnam with work experience ranging from 6 to 26 years. In-depth interviews were conducted using a lifeline chart. The constant comparative method was applied for cross-comparison between cases. The study results revealed four career phases, including Phase I: Adaptation and competency building (1 to 5 years of work experience), Phase II: Stabilisation (6 to 10 years of work experience), Phase III: Prosperous engagement (11 to 20 years of work experience), and Phase IV Calming down or winding up (21 or more years of work experience). The findings may help administrators tailor teacher educators’ professional development based on their experience and expertise. Since there was a limited number of participants, generalisation can be made only under suitable contextual considerations.

First, the definition of the term ''teacher educators'' has been discussed in depth (Lunenberg et al., 2014;Murray et al., 2021;S. White, 2019).Lunenberg et al. (2014) used a broader definition that considered teacher educators as anyone supporting the professional development of future teachers.Furthermore, S. White (2019) added another group called ''community-based teacher educators,'' who work outside higher education institutes (HEIs).Recently, Murray et al. (2021, pp. 3-4) synthesized three types of teacher educators, which are: 1) Traditional teacher educators employed and working at HEIs. 2) Mentors or supervising teachers overseeing student teachers' practicums or newly qualified schoolteachers.3) School-based teacher educators.This categorization indicates that teacher educators are a heterogenous group because of their different work contexts, despite being labeled under a single term (Izadinia, 2014).These different contexts govern the professional learning of teacher educators to satisfy their professional needs (Koster et al., 2005;Lunenberg et al., 2017).
In this study, the term ''teacher educators'' refers to individuals who teach subjects or didactics at teacher education institutes.This definition was established because teacher educators' diverse work conditions impose different requirements regarding educational diplomas, job expectations, and workplace missions (Koster et al., 2005).Furthermore, such diversity makes the comparison of data from divergent groups to meet the research purpose a difficult process.Swennen et al. (2010) clarify the identities and roles that teacher educators hold in HEIs by identifying four sub-identities of teacher educators: schoolteacher, teacher in higher education, teacher of teachers, and researcher.They are also reported to have six working roles: teacher of teachers, researcher, coach, gatekeeper, broker, and curriculum developer (Lunenberg et al., 2014).Due to teacher educators' complex working environments, including diverse subjects and stakeholders (e.g., student teachers, colleagues, administrators, and other external stakeholders), satisfying said roles' requirements is a demanding task.Both novice and expert teacher educators frequently face situations that require thorough knowledge, experiences, and resilience to overcome challenges (Lunenberg et al., 2014).
Research also shows that beginning and experienced professionals have different concerns and professional needs (Swennen et al., 2009;Vanassche et al., 2021;Van der Klink et al., 2017); in other words, their professional needs change on the basis of their expertise level.However, little is known about how teacher educators' career phases are featured throughout their mid and late career, while considering the duration of each phase (Murray et al., 2021).Possible incidents and hinderances leading to negative or productive professional tracks are currently unexplored.Additionally, the existing literature on the career stages of teacher educators mostly concerns the induction and beginning stages (Murray & Male, 2005;Murray et al., 2021;Van der Klink et al., 2017).Hence, this study aims to understand this issue by exploring the characteristics of each professional life phase throughout a teacher educator's career.The term ''professional life phases'' refers to the different stages of a teacher educator's career (Day & Gu, 2007).Each phase contains its leitmotif which influences professionals' progression and satisfaction (Floden & Huberman, 1989).Many research has specified schoolteachers' career phases with different teaching perception, professional learning activities and sub-groups for each phase (Fessler, 1995;Huberman, 1989;Sikes et al., 1985); however, the same has not been done for teacher educators.The findings of this study might support efforts to prepare future teacher educators so that they are ready to take on the roles awaiting them in HEIs.They also raise the administrators' awareness of the adequate involvement and autonomy that are essential for these professionals at each career phase.
In addition, more research has been conducted on teacher educators in the Anglophone and Middle-East contexts, compared with the Asian context.When national and local contexts are under-researched, it is difficult to form a knowledge base for the ongoing professional development of such professionals (Cochran-Smith et al., 2019;Murray et al., 2021;Tack et al., 2021).Therefore, this study treats Vietnam as a case study to add to the literature.

Research Purpose and Questions
This study explores the characteristics of each professional life phase in the careers of teacher educators in Vietnam.Therefore, the following research questions were formulated: 1) What are professional life phases of Vietnamese teacher educators?2) What are Vietnamese teacher educators' concerns in each phase?

Literature Review
Professional life of teacher educators begins when they entry the profession.Each phase in the professional life spans a certain duration, when it is fruitful moments for specific activities (Floden & Huberman, 1989).Phases are sequential which bases on professionals' experience rather than age or position (Day et al., 2006).It is the professional life phase that controls teachers' effectiveness and commitment.Each phase is featured with its different professional learning motivations, concerns, and identities (Louws et al., 2018).Those professional concerns and learning needs can be addressed by tailoring organizational and personal support for each separate phase (Day & Gu, 2007).Besides, professionals can move in and out of phases during their career due to personal, organizational, and work-related reasons (Fessler, 1995).Differences about concerns among early-, mid-, and late-career phase teacher educators are reviewed below.
Although prior studies on the professional phases of teacher educators' careers are scarce, researchers like Cochran- Smith (2003), Swennen et al. (2009), Ben-Peretz et al. (2010), Brody and Hadar (2011), Dengerink et al. (2015), and Van der Klink et al. (2017) have highlighted this topic.Ben-Peretz et al. (2010) studied experienced teacher educators who reflected on their entire career and noted that they faced continuous changes that led to distinctive phases in their careers.From the early-career phase onward, they looked for support to establish their identities and adapt to their new roles as teacher educators (Shagrir, 2010).Murray and Male (2005) showed that the mid-career transition from schoolteacher to early-career teacher educator causes frustrations and uncertainties.Despite beginning teacher educators being excellent school teachers, their prior teaching experience at schools is not automatically transferred to their new workplace (van Velzen et al., 2010).Working with adult students is a challenge, which includes tasks of lesson preparation, assessment, the use of adequate teaching styles, coping with students' motivation, and research challenges (Loughran & Hamilton, 2016;Swennen et al., 2009;van Velzen et al., 2010).Paradoxically, beginning teacher educators rarely undergo an induction process to acclimate to the institution and profession (Harrison & McKeon, 2008;van Velzen et al., 2010).To overcome these difficulties in the transition period, they seek collaborative learning with more experienced teacher educators, sharing problems with other beginning teacher educators within and outside the institution and seeking their feedback (Shagrir, 2010).MacPhail et al. (2019) found that early-career teacher educators are more inclined toward interacting with more experienced teacher educators, rather than others in the same cohort, and within their university, rather than with colleagues from other academies.Beginners prefer learning individually, for instance, by attending courses on teacher education and seminars (Dengerink et al., 2015).They also learn through trial and error by supervising student teachers (those who take teacher education for their undergraduate education) and reflecting on their own teaching practices (Berry, 2021).During the induction period, teacher educators are not specifically interested in doing research, as they do not see a positive correlation between research and teaching (Loughran & Hamilton, 2016;Murray & Male, 2005); however, they expect to be informed about research, policies, and advancements in the field (Swennen et al., 2009).Those with less than 7 years of experience as teacher educators show the highest level of interest in reading scientific and professional literature and doing research (Dengerink et al., 2015).Their research impulse is stronger than those with over 7 years of experience (Dengerink et al., 2015).Previous studies show that beginning teacher educators manage their learning to adapt with new environments (Boei et al., 2015;Murray, 2016;van Velzen et al., 2010).These features coincide with what early teachers experience in the induction phase, where they move from being student teachers to classroom teachers (Smith, 2005).
Ben-Peretz et al. ( 2010) found that, teacher educators attain mastery over their teaching practice in the midcareer phase; therefore, they wish to disseminate wisdom through writing and evince strong interest in publication.Some proceed to embark on a managerial track.Van der Klink et al. (2017) also described the inner transitions of the concerns of experienced teacher educators from 10 countries, including the Netherlands, Israel, Japan, Australia, the Czech Republic, Belgium, Slovenia, Spain, Turkey, and the United Kingdom.They described a shift, going from beginners with survival concerns to more reflective practitioners who are self-aware of their ongoing professional development.Additionally, midcareer teacher educators shift their concerns from selfadequacy to student teachers' empowerment (Van der Klink et al., 2017).They acknowledge the significance of research for their professional development and reputation, which differs from early-career teacher educators' perceptions.These experts are more inclined to join in or lead a group research endeavor and professionally interact with external experts rather than to peer-coach or participate in courses (Byman et al., 2021).They are interested in contributing to the profession, enabling knowledge development, and learning by publication (Shagrir, 2021).They rely on independent learning to acquire information about research methods, the literature, and academic writing (Ping et al., 2018).Furthermore, enthusiastically engaging in congresses and conversations with external colleagues fosters academic exchange and enrichment (Dengerink et al., 2015).
At the end of the professional cycle or late-career phase, when they inch closer to retirement, their concerns pertain to teacher education, but less specifically to their work, as they suffer professional fatigue (Ben-Peretz et al., 2010).These professionals are absorbed in selfdevelopment or enlightenment and honing of personal and international skills, such as listening, empathizing, or mediating (Ben-Peretz et al., 2010).
Previous studies have shown general changes in concerns and professional development activities undertaken by teacher educators at early-, mid-, and latecareer phase.Each phase in their career path embraces different beliefs, attitudes, and preferences (Brody & Hadar, 2011).However, no single theory has illustrated teacher educators' transition between their different career phases according to the number of their working years.Hence, the present study's conceptual framework (Figure 1) has been designed to show how the research purpose is expected to be achieved.

Conceptual Framework
The conceptual framework was built on the basis of several studies on early-, mid-, and late-career teacher educators' professional learning journeys (Ben-Peretz et al., 2010;Dinkelman et al., 2006;Murray, 2016;Murray & Male, 2005;Shagrir, 2010;Smith, 2005;Swennen et al., 2009;van Velzen et al., 2010;E. White, 2014).The human life cycle in Levinson (1986) and teachers' career phases in Day and Gu (2007) were also referred to in the conceptualization process of this framework.
This framework hypothesizes that teacher educators experience four phases throughout their career course, which begins with I, II, III, and finally IV.Phase I refers to early-career teacher educators.Phase II and III means teacher educators who are in the mid-career phase.Finally, Phase IV refers to teacher educators at the latecareer phase.Each phase lasts for a number of years and is characterized by the teacher educators' varied concerns.This framework demonstrates the approach to find answers for the research questions and achieve the research purpose (Adom et al., 2018).

Ethical Approval
The Ethics Committee of the Graduate School for International Development and Cooperation at the author's institution gave ethical approval for this study on January 4th, 2021 (Extension Number 3721).

Informed Consent
An informed consent form concerning the study purpose, sampling, permission of audio or video recording, and data protection was sent to each participant via email.The participants expressed their consent through a statement via email or verbatim before being interviewed.Their names have been pseudonymized throughout the data analysis and report.After transcribing each interview, a transcription was sent to the interviewee for their confirmation.

Research Design
The grounded theory design is the most suitable to discover categories for a new theory when the phenomenon is under explored (Corbin & Strauss, 1990) this study.Theoretical sensitivity (Corbin & Strauss, 1990) of the author was constantly activated in analyzing from the first interview.After integrating emerged categories in a model, theories about human's life, teachers' life and the conceptual framework were referred to make a deeper sense about the career phases for teacher educators.

Sampling
Hanoi National University of Education (HNUE) was selected as it is the leading university in educating future teachers for the primary to secondary level in Vietnam (MOET, 2020).This study utilizes theoretical sampling because it allows to refine and supplement tentative categories in a new theory (Charmaz, 2006;Gentles et al., 2015).Theoretical sampling referred to categorized professional life phases in the conceptual framework for its sample selection.Theoretical sampling enhances the information-rich selection of participants.Additionally, it allows ongoing sampling responding to the collected data, which adds to categories emerged among random participants (Chun Tie et al., 2019).Hence, participants in this study were firstly randomly sampled based on prior-criteria.During the data analysis of interviews, purposive sampling was done to enrich the collected data.Simulation of data collection and analysis has supported sufficient data in grounded research (Corbin & Strauss, 1990).Participants were included in the sampling frame if they (1) were fully teaching at any of the 23 faculties; (2) had a public profile on the university website; and (3) provided details of their work experience in the profile.Based on HNUE's website data, 112 participants satisfied all three criteria and formed the research sample.The 112 participants were categorized into four groups based on their experience as mentioned in the conceptual framework.The information gained was as follows: 0 people at Phase I; 20 people at Phase II; 72 people at Phase III; and 20 people at Phase IV.As a qualitative study aims to investigate in-depth the person's thoughts, priorities, and experiences by maximizing text-data (Merriam & Tisdell, 2015;Renck Jalongo & Saracho, 2016) and needs at least six interviews to gain rich data in grounded theory research (Corbin & Strauss, 2008;Gentles et al., 2015), the sample size for this research was finalized as 8, consisting of 2 participants at Phase II, 4 participants at Phase III, and 2 at Phase IV.The disparity in the numbers is due to the imbalance in the number of staff in the sampling frame, where no participants under 5 years of work experience was found.Their ages ranged from 37 to 45 for men and 33 to 47 for women.As many as five out of eight, whose names have been pseudonymized as Quang, Nam, Hung, Tai, and Linh, were randomly sampled with the RANDBETWEEN function in Microsoft Excel.During interviews with randomly sampled participants, the author was aware that respondents were active in researching and teaching, and confident to participate in the study.Those who were struggling could be excluded from the study.Hence, purposive sampling was conducted by asking the participants and the author's friend to introduce other participants in each phase.As a result, the rest, whose names were pseudonymized as Tra, Thu, and Hong, were purposively sampled (Table 1).

Interviews
The interview guide included three sections: (1) background and demographics, (2) perceptions of phases in their professional life, and (3) professional learning activities undertaken in each phase.The interview questions were discussed with other senior researchers, after which the interviews were piloted in December 2020.
Semi-structured online interviews lasting between 60 and 180 minutes were conducted, while a lifeline chart was employed via Zoom software between January and May 2021 for the data collection.Interviews were transcribed verbatim.The lifeline chart of participants, who were willing to draw it, supplemented textual data during the data analysis.

Data Analysis
The constant comparative method (CCM) was used for data analysis; it was created by Glaser (1965) in grounded theory research.CCM enables the generation of the theory's properties for the studied phenomenon.Textual data were analyzed both inductively from interview's content and deductively from concepts formed in the conceptual framework.This study applied three steps of comparison in Boeije (2002).The three steps include comparison within an interview, between interviews of participants at the same phase, and finally among interviews of participants in different phases.First, open coding was done with the exact words of each participant's transcript.Personal profiles with years of work, time of obtaining degrees, and age were noted chronologically.Codes were labeled and placed into categories and subcategories (Boeije, 2002).For instance, codes such as ''low wages,'' ''have to take care of [their] family,'' and ''do other things to make ends meet'' (e.g., a case of Quang) formed the sub-category of ''concerns about life or living conditions.''While coding, temporal expressions including ''now,'' ''within 5 to 10 years,'' ''around [year],'' and ''current'' were converted into actual numbers of working years and placed beside the categories that emerged.After open-coding the first interview, the author discussed codes and categories with other researchers in a 3-hour seminar to confirm their accuracy.Some revisions of separation between categories were made.However, researchers agreed that it is the author who finally interprets data for a study (Renck Jalongo & Saracho, 2016).
Subsequently, axial coding was used to compare between codes and categories of different teacher educators in the same phase.The author went back and forth (Merriam & Tisdell, 2015) among the categories to detect different career directions of these teacher educators.
Finally, comparisons between categories of teacher educators in different phases were conducted.All similar attributes for each phase found in all participants were grouped together.Thereafter, the time-deviation of occurred incidents or categories between those in different phases were compared.The conceptual framework was referred to confirm or highlight differences found.Each phase was then named based on its general attribute and used as headings to report the data.

Findings
The data analysis presented four distinctive professional phases in a participant's life, which are: Phase I-Adaptation and competency building ( 1 Seven out of eight participants were former students at their university, including Quang, Tra, Nam, Hung, Thu, Tai, and Linh.Four of the eight worked as teacher educators right after obtaining their bachelor's or master's degrees (Quang, Thu, Tai, and Linh).The first phase was featured with personal concerns about life or living conditions; pressure to pursue further education; pedagogical concern; concern about building relationships with colleagues and student teachers; and concern about developing scientific research knowledge.
Personal Concerns About Life or Living Conditions.Apart from one male participant from an affluent family, all seven participants reported facing stress and uncertainty as a result of low starting salaries, being asked to do additional work that was not originally disclosed, and taking care of their families.Financial burdens were considered the worst experience in the early stages of their careers.As Hung said: The hardest time, I think, is the beginning, because I was distracted by both teaching and studying further [.]Dealing with the two things simultaneously as well as managing my living conditions [.]That was the time when I was confused about what I should focus on, which option was more reasonable.
Quang was a young teacher educator at the age of 37 years.He spent 3 years pursuing his PhD abroad, and said: When I returned [to Vietnam], my salary was only 2-3 million a month [150 US dollar], the rent consumed it entirely [.] Female participants bear the burden of having to balance their family duties such as giving birth, with their work and study duties.Linh noted: At that time, I had to handle my children, work, and higher education all at once.Finance was the toughest issue at the time.Even now, it is still challenging for young people.
All participants took up secondary jobs, such as parttime teaching at other universities, translating books, and doing business.Hung said that those who only taught and did research within the university suffered great hardships because of financial insufficiency.
Pressure to Pursue Further Education.As per university rules, participants must have at least a master's or PhD degree and other required certificates.In the first phase, seven respondents (except Linh) already had master's degrees.Thu shared struggles when she wished to study further.Thu said: Back in my time, the old principal had a very outdated mindset and was afraid that [if] everyone went to graduate school, no one would do trivial jobs within the faculty.I had to postpone my plan to study for a master's degree for two years after I started my job.Later, I had to pay for my master's degree.
Pedagogical Concerns.The feeling of self-adequacy about subject content knowledge and pedagogical knowledge was found among all participants.Hung said: When I first taught, I was most afraid that I had inadequate knowledge and could not convey what I wanted to.I think most young lecturers encounter this.
Nam shared the same feeling and self-doubt about his manner, knowledge, teaching methods, and the attractiveness of his lecture.Concerns about student evaluation and comparisons with expert colleagues were also mentioned by three participants (Nam, Hong, and Quang).Nam said: I kept questioning myself-Am I able to meet the job demand?Can my teachers trust me?Is my lecture fine?and tried best to prepare the lesson.
It took Nam, Quang, Thu, and Tra about 3 years to gain confidence in their respective subject areas and teaching methods.Nam confessed: You know, people said that if you want to be good at something, it takes 10,000 hours to practice.I feel that, after three years of teaching, I became proficient and confident enough and the students also gave me positive feedback.
Hong, Linh, and Tai agreed that it takes a minimum of 5 years to gain concrete knowledge, develop attractive lessons, and practice simple scientific research.This time length was also true in the case of a former schoolteacher, Hung, although he was experienced in teaching secondary students.Moreover, as Tai said: The first 5 years are basically for practicing research and to get a PhD.Those five years, I think, are to make a living by teaching [.], read more to have adequate knowledge, and learn to publish papers internationally.

Building Relationships With Colleagues and Student
Teachers.Another issue at this stage was building and nurturing harmonious relationships with colleagues and student teachers.Novices sought to gain the trust of and approval from student teachers.They wished to engage in effective communications with their students and wanted to understand learners' difficulties.Hong said: No two students are the same.Lecturers want their students to like them.It challenges lecturers to best interact with everyone and convey the lesson to each in the best way.
Having a good relationship with the students and involving them in research activities contribute to participants' positive feelings toward their teaching job.Quang said: I enjoy working with students and graduate students.I am lucky because I always conduct scientific research with my students and friends.We do research together, and our relationship is quite good.I like them and they like me.That is what I appreciate the most.
Novices also have to harmonize their relationships with other colleagues.Hierarchy at the workplace places them in uneasy situations, which hinders academic freedom.Thu said: Many say that there are ''giant shadows'' [senior professors] that are much bigger than me.When we teach and conduct research, it must be equal and unbiased.Nevertheless, our way of thinking and even future relationships are greatly influenced and dominated by the thoughts of our supervisors.
In addition, a custom of visiting people at higher positions during holidays and Tet (the Vietnamese Lunar New Year), to show respect and appreciation, was costly for beginners, as in the case of Hong.

Concern About Developing Scientific Research Knowledge.
The lack of in-depth procedural research knowledge and skills impeded invitations to join collaborative research.Research procedural knowledge (such as the ability to detect the novelty of the topic, research ethics and methods to apply for research grants) was addressed and gradually obtained during their engagement in research, as in the cases of Hong, Linh, Thu, and Quang.Linh said: I could not do it [research] right at first, they [members of the research group] told me not to reveal the children's faces in photographs.I did not understand the reason.Later I understood that if the researcher wanted to have their papers published, they must comply with research ethics.I was not taught that.
Four participants, Quang, Thu, Hong, and Nam, had to deal with budgetary issues and a lack of equipment for experiments, which stressed them out.This happened among those working in the field of natural (Quang and Nam) and social sciences (Thu and Hong).Although not much research progress was reported, the participants were concerned about the academic outputs.At this stage, basic research was done mainly for fulfilling the requirements of a master's or doctoral course and job opportunities from their own budget.Quang said: Besides ideas, it [research] requires equipment, machines, and chemicals.My research interest is also different from other colleagues in the department.In about the first two years, I did not make any progress in research, I just conducted very ordinary studies.I had to spend my own money for a while.After receiving a project funding, the research work became better.
In addition, in the beginning, participants saw research and teaching as unrelated activities.Only one participant, Nam, who had a famous field expert as a supervisor and was spared financial worry, was motivated to produce a number of scientific papers even before his PhD.

Phase II-Stabilization (Participants hHaving 6-10 Years of Working Experience)
All participants had master's degrees at this time in their careers.Seven of them, Nam, Hung, Tai, Hong, Thu, Linh, and Tra, were enrolled in doctoral courses (Table 2).
Based on the participants' priorities toward fulfilling the five concerns mentioned in Phase I, two subgroups were identified.The first one, namely, developing a sense of self-efficacy, included five participants: Quang, Nam, Thu, Tai, and Linh.This group steadily improved its living conditions, got promotions, either obtained PhDs or were about to obtain them, had published papers in international journals, and preferred to research over teaching.Linh had become the Deputy Head of her faculty from the 5th to 10th year of work.Tai was about to obtain his second doctorate.
The second group, namely struggling to attain selfefficacy, included three participants: Tra, Hung, and Hong.This group faced one of these situations: (1) Overfocus on improving living conditions (case of Hong); (2) Prolonged period to obtain a PhD (case of Hung); and (3) Failure in obtaining a PhD (case of Tra).
The milestone selected to direct a participant toward group 1 or 2 was their success or failure in their doctoral programs with proper foundation of research procedural knowledge and skills.Table 2 shows that all male participants obtained PhDs or joint-degrees abroad within the first 10 years of work, meanwhile three out of four females obtained their PhDs at home within the first 15 years of work.
All participants who had PhDs in developed countries agreed that they had become mature and independent after their doctorates.The doctorates that were obtained abroad bestowed them with reduction of life burdens owing ''to the scholarships,'' ''academic freedom'' and ''time to intensively work on research,'' proper training of how to conduct a scientific research, ''improvement of English,'' and ''motivations given by international professors and colleagues,'' as Tai, Quang, Hung, and Nam reflected.
Nam said: My time as a PhD scholar made me mature and changed me completely.I understand how to work academically independently, find and solve research problems, and write journal articles [.] that is truly independent and At this stage, participants published papers in domestic and/or international journals and joined diverse groups of researchers both within their colleagues at the university level and in other universities and external research institutes (Quang, Nam, Tai, and Linh).For those belonging to group 2, it was not until the accomplishment of their PhD that they felt relieved to ''stand on their own feet,'' as Hung noted.The impact of this situation can be seen in the lifeline chart of Hung (Figure 2); before obtaining his PhD in the 8th year of work, his career had stagnated.
Those without an intense period of research abroad took care of simple tasks in the research progress to learn research skills.As Linh said: I participated in different research groups to learn from my colleagues.At the beginning, I took care of simple tasks like collecting the data.Once I became experienced enough, I was able to take the lead.We should be patient.
To overcome challenges to build academic adequacy, the thirst for learning and exploring new ideas was essential.Five participants in group 1 were students who excelled at least in high school.Tai, a professor with two doctorate degrees who described himself as someone ''born to be a teacher,'' had been receiving scholarships since grade 4. Nam, a student at a school for gifted students, spent money on books instead of visiting his teachers on Vietnamese Teachers' Day.Quang scored the highest marks in the national examination for his block subjects.Thu and Linh graduated with distinction.Linh even had three bachelor's degrees in fields of education.
Participants in group 2 also had strong profiles.However, facing one of three aforementioned situations affected their motivation to be active in research activities.Hong said: I have published papers in domestic journals alone.I am under-confident [.]I love sitting to think and write.Yet, I am too busy, tired with financial pressures and taking care of two children.
This group preferred to teach rather than conduct research.These professionals had developed proper teaching styles and received good feedback from student teachers on their pedagogy.

Phase III-Prosperous Engagement (Participants Having 11-20 Years of Work Experience)
Two groups of participants were further divided as a continuation of the division at Phase II.The first was named proactive engagement in research and teaching, comprising Tai, Linh, Thu, and Nam, and the second was named holding but losing commitment, comprising Tra.
The first group had attained all diploma requirements of their respective workplaces.Full of energy, free of pressure to acquire diplomas, and with grown-up children, the members of this group were found to be in a stable financial state, filled with subject content knowledge; they were awarded promotions to higher academic positions and had obtained a good standing within the research community.All five participants with 12 or more years of experience concurred that this stage was the prime of their careers, affording them proactive engagement with research and teaching.Tai reflected on his three continuous post-doctoral years to research abroad, when he was approximately in the 10th year of working.He said: After my doctoral studies, I went to many places and research centres abroad and achieved a lot.I defended my doctoral degree (habilitation) abroad.At home, I got promoted to be an associate professor.I received that rank at a relatively young age, more than 10 years ago [age 35 years].I was fully energetic with respect to producing academic publications.
Linh and Thu reached their prime after gaining 15 years of experience.As Linh said: About 5 to 7 years ago [15th year of experience], 1 or 2 years after my PhD, I was full of energy.My children have grown up now.I have more time to dedicate to the profession.A mutually beneficial relationship between teaching and research emerged at this stage.Teaching was both a source of research ideas and a channel to disseminate research results.Meanwhile, research deepened teaching knowledge as Linh reflected.More collaborative learning from doing research with their students gave room for teacher educators' learning in case of Thu.Participants transferred from a knowledge transmitter into a facilitator.Thu said: I am not greedy for knowledge [in teaching] anymore, I see that I have to guide [student teachers] and not just provide knowledge.I only suggest and facilitate; they have to collect knowledge by themselves.
Issues faced by this group included the pressure to publish more, which Nam, Hung, Thu, and Tai mentioned.Participants in the humanities and social sciences were more challenged with quantitative studies and internationally published articles than those in the natural sciences.Proficiency in the English language challenged professionals in both fields.Awareness of the inferiority of social studies over natural sciences was raised if their qualitative research did not address contemporary social issues.Thu said: First, I only did qualitative research, which relates to the theoretical framework, not applying research.However, if I wanted to publish the papers internationally, statistical data was a must.Due to this pressure, I will probably have to deal with quantitative studies; yet, to do that, the first problem is funding; the second is how passionate I am to do that.
Nam also experienced the pressure of having to produce research for his funded projects.He said: ''I am under great pressure while waiting for the reviewers' feedback.I do not know the fate of that particular article, leading to many sleepless nights.'' The second group had one participant who considered working at the university a benefit for her business.Tra said: When I had children, my income was not enough to cover our living expenses.I thought about quitting my job.The only reason I continued working as a teacher educator was that it enhanced my reputation and helped my business.
She did not expect promotions to higher ranks, as she was more interested in her secondary job.She kept her research output to a minimum, aiming only to fulfill her job requirements.She did not engage in collaborative research and relied on self-study in the course of her teaching and research work.On being asked about her future plans, Tra said: I want to stay on in the profession.I do not expect a promotion.I hope to do well in other side jobs due to the prestige from this profession.Professional activities, which contribute to society, were prioritized despite being considered a ''silent contribution.''Tai also raised the problem of performancebased evaluation, which involves counting professors' research articles on ''international journals with high impact factors'' instead of considering the social value of their work such as ''writing textbooks.'' Tai was motivated to work directly with school children to share his wisdom and impart moral lessons so that he could foster their talent.He resumed this activity after a 10-year hiatus.
I teach the eighth and ninth grades.I am interested in teaching able students.In the mathematical environment, I train their mindset and personality.
The ''give and take culture'' was acknowledged, so he tried to support young generations by deeds such as writing recommendation letters for their promotion or studies abroad and also defended his young colleagues.
Developing empathy and becoming more humane toward younger generations also emerged in the stories of a female participants.As Linh said: I learned to trust student teachers better.While working in groups, I listen to people's stories and encourage them when they achieve something, even if it is minor progress.I feel they enjoy working with me more.
Both Linh and Tai, expressed an intention to continue teaching and pursuing future studies when they were asked about their future plans.
Anticipating the next career phase after the current one, Linh reflected that her female colleagues aged 50 years or more, close to retirement, had reduced energy for work.They were not interested in undertaking major or long-term research projects because of fatigue.New ideas for projects lessened and they tended to think conventionally.Research groups no longer wanted to involve them and looked for professors with more innovative ideas instead.This stage was described as a winding up phase in their careers.
Figure 3 presents the four phases in the lives of Vietnamese participants.The black arrows present the shift to the next phase.The dotted lines imply possible routes for movement or switching between phases.Professionals in Group 2 of Phase II can proceed to Group 1 of Phase III despite being struggled at the early phase.Professionals in Group 2 of Phase III and in Phase IV: Calming down can enter Phase IV: Winding up before their career exit.

Discussion and Conclusion
The findings highlight that participants' concerns shift during four professional life phases in their careers.The first phase-adaptation and competency buildingfeatured concerns about living conditions, the pursuit of higher education, pedagogy, relationships with colleagues and student teachers, and the development of scientific knowledge.Their worry about teaching and researching was considered to be typical for those at the early-career stage, which concurred with previous studies on the professional challenges of novices in terms of content knowledge, pedagogical knowledge, and research activity (Maaranen et al., 2019;Ping et al., 2018;van Velzen et al., 2010).Participants showed interest in academic writing and publications; however, they did not acknowledge the mutual benefits between research and teaching.Previous studies also described that early-career teacher educators found the two duties of teaching and research separate and in competition with each other (Loughran & Hamilton, 2016;MacPhail et al., 2019;van Velzen et al., 2010).Beginner professionals share similar worries as beginner school teachers who start discovering the basics of the profession (Guskey & Huberman, 1995).However, Vietnamese professionals also concern about dealing with financial pressures due to low starting salaries, which relates to worries about job sustainability of beginners (Maaranen et al., 2019).The challenging financial situation required young professionals to astutely balance professional self-development and making ends meet.Overfocus on either of them affected their motivation and energy for work.This directs their entry of the next phase in which teacher educators are able to develop the sense of efficacy or struggle to grab necessary knowledge and skills for their work.
The acknowledgment of concerns of teacher educators at the first phase calls for the need for support to eliminate financial burdens on learning activities of novices, spare them unnamed tasks, actively include them in the academic activities of the practice community, strengthen on-the-job training for research, and provide them opportunities to have their graduate education abroad in  a research-intensive environment.Since teacher educators are keen on personal development, opportunities for learning should be practical considering their specific concerns (Berry, 2021;Vanassche et al., 2021).
The second phase lasted from 6 to 10 years of work experience, featuring participants' attempt to stabilize their sense of self-efficacy in their jobs.In this stage, teacher educators, who had already succeeded in gaining the required diplomas, began building their mastery in teaching and confidence in research; contrarily, those failing to get further education faced losing commitment to the profession by focusing more on side jobs.Those who attempted to develop a sense of self-efficacy became more active in communicating with their colleagues in and out of their university and engaged in research projects, which concurs with previous studies (Byman et al., 2021;Van der Klink et al., 2017).In Vietnam, male teacher educators are more active and have more time to engage because they are not burdened by family duties.In contrast, female teacher educators are likely to prioritize their time toward fulfilling family duties.
In the subsequent phase, teacher educators attained mastery in their teaching and research collaborations, which grew if they were adequately equipped in the previous stage.They were transformed from being ''knowledge consumers'' to '''knowledge producers'' (Clemans et al., 2010) by actively publishing articles in both domestic and international journals (Dengerink et al., 2015).The interrelation between teaching and research was valued by these professionals (Ping et al., 2018).Consequently, promotion to managerial positions was common at this stage (Ben-Peretz et al., 2010).For this active group, it is important to pay attention to support for research equipment, budgets, diverse research methodology, and English writing for publication.Additionally, they reported a need for a room for professional autonomy and maintenance of their mental well-being, since they engaged in a variety of academic tasks in and out of their workplace.This confirms findings from previous studies stating that senior teacher educators concern about their well-being due to over-workload and lack of time (Maaranen et al., 2019).Besides, those in less productive groups at both Phases II and III not only required professional support but also needed career orientation to the more productive tracks in accordance with the institution's mission.
In the last phase, teacher educators in the calmingdown group showed high levels of commitment and active engagement in the profession, which has not been reported in past studies.Therefore, at this stage, they developed an interest in building empathy toward younger generations and were involved in giving back to society by directly teaching schoolteachers and dealing with matters that emerged in lower education levels.This finding is similar to those of Ben-Peretz et al. (2010), who showed that teacher educators on the edge of retirement prefer learning interpersonal and personal skills.Since experts reaching the last career phase had a higher awareness of social contributions in their academic life, it is significant to consider diverse approaches toward their work evaluation rather than adhering to the current performance-based system.This finding recalls a statement about values of the teacher educators which lies in teaching, researching and social service or contribution, which should be the basis for their work evaluation (Harrison & McKeon, 2008;MacPhail et al., 2019).The winding-up stage is hypothesized from the literature review, which mentions that professional fatigue occurs when they are close to retirement (Ben-Peretz et al., 2010;Day & Gu, 2007), and the interviews of teacher educators.These professionals experienced a plateau in their career.Further study is necessary to examine the features of those who experience this winding-up phase.
In general, the dual track of teacher educators reflects the non-linear characteristics of their professional life phases, which are also found in the cases of schoolteachers and people in general (Fessler, 1995;Guskey & Huberman, 1995;Huberman, 1989).Teacher educators need to manage their ongoing professional development with determined effort in the earlier phases to advance to subsequent productive ones (Berry, 2021;Tack et al., 2021).Failing to prepare adequately causes their years of working experience to mismatch the expected level of expertise.

Limitations
This study has some limitations.First, as there was a limited number of participants, generalization can be made only under suitable contextual considerations.Second, the samples in this study were chosen using random and purposive sampling, which is not consistent.However, the data show that one in three teacher educators purposively sampled was active in their professional development, whereas one struggled, and one showed no interest.Thus, purposive sampling allowed this study to include voices from marginalized groups.Third, because of the COVID-19 pandemic, the researcher had to rely on online platforms for interviews.Lack of direct interaction and the feeling of information insecurity might make the participants reluctant to mention policy-related issues.Fourth, this study did not include the voices of teacher educators with over 21 years of experience, who were in the winding-up phase.Thus, this stage was not supported by empirical data.Additionally, due to the imbalance of young teacher educators in the sample, no participants with less than 5 years of work experience were included.However, relying on the rich literature on novice teacher educators and data saturation found in the interview data of studied professionals led to the generation of Phase I. Longitudinal studies will be useful to examine the transformation of individual teacher educators across phases to validate the utility of the present findings.Additionally, this study mainly utilized a single data collection method with in-depth semi-structured interviews.Mix-method or other research designs may enrich and triangulate data on findings for research on life phases, hence, further study is encouraged to cope with this methodological limitation.
-5 years of work experience); Phase II-Stabilization (6-10 years of work experience); Phase III-Prosperous engagement (11-20 years of work experience); and Phase IV-Calming down or winding up (21 or more years of work experience).Each phase had room for 2 years of deviation to mark late or early entry/exit.Phase I-Adaptation and Competency Building (Participants Having 1-5 Years of Work Experience)
Phase IV-Calming Down or Winding Up (Participants Having 21 Years or More of Work Experience)At the calming down phase, participants including Tai and Linh had high autonomy to control their workloads and continue to balance research and teaching.Besides, they focused on social contributions and developed their interpersonal skills while working with others.As Tai said:Being a Professor, I have gained more self-control.I only do what I consider meaningful.I do not do anything that is frivolous, as I did when I was young.

Figure 3 .
Figure 3. Dual track of professional life phases of Vietnamese teacher educators.
. Grounded theory framework by Chun Tie et al. (2019) informed Figure 1.Professional life phases of teacher educators.

Table 1 .
Details of the Participants.

Table 2 .
Details of Participants' Doctorate Degrees: A Milestone.
autonomous in scientific research.The independence and autonomy are shown from planning your research, experimenting, and publishing an independently authored paper.I acknowledge the academic maturity I gained.Tai said: Having your doctorate abroad, you can research intensively and have some savings from the scholarship.It is little, though.