Constructing a teaching capability maturity model for content and language integrated learning teachers in Taiwan

The national policy of bilingual education will inevitably entail a demand for content and language integrated learning (CLIL) teachers. Consequently, feasible and sustainable CLIL teacher education in Taiwan will be required. This study explored a teaching capability maturity model for CLIL teachers based on the level of maturity of teachers’ teaching capabilities. The modified Delphi method and fuzzy analytic hierarchy process were used. Purposive sampling was employed to recruit 33 interdisciplinary professional CLIL teachers. The three most important levels in the model were the basic course management, advanced course management and implementation, and initial levels. Implications of the results are discussed and suggestions for CLIL teacher education are proposed, such as emphasising the development of course management capabilities and providing teachers with practical experience in teaching content subjects.


Introduction
T eacher training for compulsory education not only forms a critical foundation for national development but also determines the quality and competence of citizens. Regarding Taiwan's teacher education system, the Teacher Education Law was renamed to the 'Teacher Education Act' and amended in February 1994, thereby changing the country's teacher education from a unitary, plan-based, and state-financed and -directed teacher preparation system to a multidimensional, personnel reserve-oriented, self-sponsored, and selection-based one. After several amendments, the Teacher Education Act was again amended in June 2017, with a focus on reforming the teacher qualification test and promoting the education internship system; preservice teachers were now required to take the qualification test before commencing their internship. In addition, the newly amended regulations for teacher development programmes allowed universities in Taiwan that provide teacher education programmes to establish their own preservice teacher programmes, which are student learning oriented, and to develop competent teachers and equip them with practicability to satisfy the requirements of education. Teachers play a crucial role in building a nation because education determines competitiveness. Teacher development in Taiwan is focused on helping preservice teachers acquire educational knowledge and skills, develop professionalism and a global perspective, and learn to respect different cultures and embrace diversity (Ministry of Education [MOE], 2017). Teacher education programmes help preservice teachers develop enthusiasm for teaching, a sense of professional responsibility, and the knowledge, skills, and attitude required for the profession of teaching. Teaching internships, as a part of teacher education programmes, provide preservice teachers with opportunities to utilise theoretical knowledge in practice and gain hands-on experience.
In 2018, the Taiwanese government announced its bilingual nation policy to transform Taiwan into a Mandarin Chinese-English bilingual nation by 2030 (Blueprint for Developing Taiwan into a Bilingual Nation, 2018; BDTBN). To achieve the policy's goals, a content and language-integrated learning (CLIL) approach was proposed for English teaching. Studies have indicated that CLIL, an innovative approach to language teaching, can lead to success in students' learning of a foreign language. In the practice of CLIL, Taiwanese English teachers are expected to teach English classes or other school subjects (such as arts, integrative activities, and mathematics) using English as the medium of instruction (BDTBN, 2018).
The national policy of bilingual education will inevitably entail a demand for CLIL teachers. Consequently, feasible and sustainable CLIL teacher education must be provided in Taiwan. A framework of capabilities required for CLIL teachers in Taiwan is also required. In response, this study constructed a teaching capability maturity model (TCMM) for preservice CLIL teachers based on the maturity levels (MLs) of preservice teachers' teaching capabilities. The objective of creating this TCMM is to promote preservice teachers' professional development towards the ideal image of professional teachers. This model was created for professional and sustainable teacher development and to gradually enhance preservice teachers' professional capabilities towards their ultimate goals. On the basis of this background, this study attempted to achieve the following research objectives: 1. To screen and select the benchmarks and framework for the TCMM for preservice CLIL teachers using the modified Delphi method (MDM). 2. To establish the dimensions and framework of the model through fuzzy hierarchy analysis.
In addition, the authors detailed the implications of the study's findings on teacher education for CLIL. This study aimed to elucidate the teaching capabilities of CLIL teachers and propose a framework for CLIL teacher knowledge (cf. Marsh et al., 2011).
Literature review TCMM integration. To explore teaching quality in higher education, Chen and Kuo (2011) examined college teachers' teaching processes in terms of Crosby's staged quality improvement. On the basis of the capability maturity model integration (CMMI) system, Chen and Kuo (2011) developed the TCMM Integration (T-CMMI), which highlights the processes, actions, and ongoing improvements in teaching. The T-CMMI comprises systemised components of teaching-related process areas (PAs), and each PA entails specific goals and practices. Depending on the staged themes, each process domain has quality improvement stages and contents, which form the MLs. In addition, the depth of the capability level (CL) can be improved for each PA individually.
The T-CMMI proposed systemic and sustainable goals to help teachers continually improve their teaching approach and outcomes for different MLs and CLs (Chen and Kuo, 2011). Table 1 presents the CLs and MLs of the T-CMMI. Table 1 Teaching capability maturity model (TCMM) integration maturity levels (MLs) and capability levels (CLs).

MLs CLs
1. Initial: a lack of specific teaching processes and inability to replicate successful teaching experiences in other courses.
0. Incomplete: inability to satisfy one or more specific goals (SG) of a process area (PA). 2. Managed: the course management process is planned and the monitoring and control are executed in accordance with the plan. Teaching is appraised, and teaching-related output is managed.
Development of CLIL in Taiwan. Taiwan has increasingly promoted CLIL teaching models. Education administration authorities of county and city governments have cooperated with universities to provide CLIL training courses. A cooperative teaching mechanism involving English teachers and teachers of other fields has been established to help teachers understand the essence and teaching framework of CLIL and implement experimental CLIL courses in elementary and secondary schools in each region. The CLIL teaching method does not entail English-only teaching. Teachers of each subject can determine the proportion of Chinese and English lectures and teaching models depending on the attributes and learning goals for the subject. Currently, all levels of schools are promoting diverse CLIL teaching projects to enable subject knowledge and language acquisition through effective teaching activities (Lu and Yuan, 2020). In addition, Taiwanese linguists Tsou and Kao (2018) developed a CLIL teaching resource book which explores the application of CLIL in various disciplines and provides a theoretical basis and framework for bilingual course design. The advantage of CLIL lies in its conformity to current worldwide development trends. Its framework can be adjusted depending on the resources and needs of different regions. Furthermore, CLIL is a literacy-oriented teaching method that satisfies the 12-year national education curriculum guidelines.
CLIL approaches. CLIL is defined as 'a dual-focused educational approach in which an additional language is used for the learning and teaching of both content and language' (Coyle et al., 2010, p. 1). With a CLIL approach, nonlanguage content is taught with and through a foreign language (Eurydice, 2006). In Europe, CLIL has been adopted as an educational approach in various educational environments for over two decades. To help prepare qualified CLIL teachers in Europe, Marsh et al. (2011) proposed the European framework for CLIL teacher education, which defines the professional competences required for a CLIL teacher and describes modules and components linked to the development of CLIL teacher competences. This framework consists of three modules, each of which contains nonsequential components. The modules and components are as follows (Marsh et al., 2011): Module 1: Approaching CLIL, which comprises four components: situating CLIL, adopting action research, examining effective pedagogy and CLIL, and focusing on CLIL in the school context.
Module 2: Implementing CLIL, which comprises five components: designing CLIL classroom curricula, anchoring CLIL in the classroom, interweaving psychological and pedagogical aspects in the CLIL classroom, accessing and adapting CLIL learning resources and environments, and becoming an evidence-based practitioner.
Module 3: Consolidating CLIL, which consists of three components: assessing for learning, networking locally, nationally, and internationally, and practising CLIL.
These modules are used to help CLIL teachers develop the professional competences for CLIL, such as (1) personal reflection, (2) CLIL fundamentals, (3) content and language awareness, (4) methodology and assessment, (5) research and evaluation, (6) learning resources and environments, (7) classroom management, and (8) CLIL management. Module 1 provides CLIL teachers with training in personal reflection, CLIL fundamentals, content and language awareness, and research and evaluation. Module 2 equips teachers with knowledge of learning resources and environments, classroom management, and CLIL management. Module 3 helps CLIL teachers develop competences in methodology and assessment. Through these modules, CLIL teachers can develop competences to 'teach content subject and an additional language in an integrated manner' (Marsh et al., 2011, p. 6).
Studies have explored issues related to CLIL such as the implementation of CLIL (e.g. McDougald, 2016), the development of teaching materials (e.g. Bailey, 2015;Banegas, 2016;Mehisto, 2012;Pérez and Malagón, 2017), teacher education and professional development (e.g. Banegas, 2012;Marsh et al., 2011;Pistorio, 2009), and assessment (Pérez and Basse, 2015;Leal, 2016). In the implementation of CLIL approaches, four matters must be considered: opposition to language teaching by content teachers, the experimental nature of CLIL programmes, the lack of second-language acquisition skills in content teachers, and the lack of CLIL teacher education programmes (McDougald, 2016). Studies have also identified the challenges teachers face in implementing CLIL approaches, such as increased workload, a lack of teaching materials, the complexity of CLIL instruction, and a lack of linguistic and methodological competences in content teachers (Alonso et al., 2008;Cabezas Cabello, 2010;Infante et al., 2009). To overcome these challenges, teacher training must address teachers' needs, including language skills, teaching competence in the target language (Fernández and Halbach, 2011), knowledge of bilingual methodology (Pena Díaz and Porto Requejo, 2008), and knowledge of CLIL (Rubio Mostacero, 2009). According to the language triptych in the CLIL framework, the required language competences for content teachers are interpersonal social language use, cognitive academic language use, pronunciation, and improvisation in the target language (Martín del Pozo, 2011).
Maturity model for teaching capabilities of CLIL teachers. This study involved the development of a maturity model for the teaching capabilities of CLIL teachers. In this model, the development of teaching capabilities is related to the required competences for CLIL teachers. By adapting T-CMMI and integrating teacher capability-related studies, the authors developed the TCMM for CLIL teachers (Table 2). This model consists of five levels: the initial level (ML1), basic course management (ML2), advanced course management implementation (ML3), quantitative management (ML4), and sustainable optimisation (ML5). Each level comprises 4-6 components for a total of 25 components. The goal of this model is to guide CLIL preservice teachers to progress from basic to advanced professional maturity and continuously pursue professional development. The levels and components of the model are as follows.
Initial level (ML1). The initial level is for CLIL teachers to understand the required education theories, knowledge, and required education theories and knowledge and develop appropriate attitudes. The 'education theories and knowledge,' 'education environment contextual knowledge,' and 'learner development theories and knowledge' components are based on Wu (2010), the Teacher Professional Standards Guide (MOE, 2016a), and the Teacher Professional Literacy Guidelines (MOE, 2018) ( Table 2). This study referenced Teng (1995) and the selforiented learning tendency scale developed by Shih et al. (2011) to incorporate 'learning enjoyment' as a component of the initial level. The collaborative learning-related studies of Huang and Lin (1996), Huang et al. (2011), andLai (2016) were referenced for the 'mutual dependency' component.
Basic course management (ML2). On the basic course management level, CLIL teachers master the teaching domain, the content of a subject, and subject-specific knowledge to achieve teaching objectives. In addition, they learn to plan their teaching methods. The 'subject content knowledge,' 'subject teaching 1-2 Educational contextual knowledge To research educational and multicultural issues; to understand school-based and local resources and culture; to keep abreast of educational trends and problems; to integrate these issues in curricula and teaching; to be aware of the influence of the educational environment on student learning.

MOE (2016a, 2018)
1-3 Theoretical knowledge of learner development To understand students' physical and mental traits and cognitive development; to understand students' backgrounds and interests; to guide appropriate learning and development for students.

MOE (2016a)
1-4 Enjoying learning To understand learning methods; to maintain interest in learning and a positive attitude towards learning. Teng (1995); Shih et al. (2011) 1-5 Mutual dependency To allow group members to be responsible for their learning as well as that of other mutually dependent members with whom they cooperate to complete tasks. Huang and Lin (1996) 2-4 Active learning capability To allow individuals to engage in active thinking and learning for each time frame and theme; to know where to acquire required information for pedagogical knowledge and skills; to determine content and methods of learning. Teng (1995); Shih et al. (2011) 2-5 Problem-solving capability To allow group members to discuss face to face and solve problems to complete an assignment. Huang and Lin (1996); Huang et al. (2011);Lai (2016) Advanced Course Management and Implementation Developing capabilities of content teaching and classroom management 3-1 Content teaching capability To employ various teaching strategies to maintain students' attention and interest based on student learning development and needs; to provide experiences to help students understand content through various media, learning technology, and resource-assisted teaching methods. Pan et al. (2004); MOE (2016aMOE ( , 2016bMOE ( , 2018 3-2 Classroom management capability To establish classroom rules and safe and interactive learning environments; to take care of individual students and encourage positive behaviour where appropriate; to create a caring and friendly rapport between teachers and students. Pan et al. (2004); MOE (2016aMOE ( , 2016bMOE ( , 2018 3-3 Student counselling capability To apply relevant principles and techniques to provide student counselling; to understand and respect differences in students' physical and mental development, socioeconomic backgrounds, and cultural backgrounds; to provide timely support and counselling when required. MOE (2016aMOE ( , 2016bMOE ( , 2018 3-4 Communication coordination capability To apply multidimensional communication approaches and skills to collaborate with other teachers to develop and integrate courses; to communicate and collaborate with school administrative personnel; to establish strong partnerships with parents and community members. Wu (2010); MOE (2016a, 2016b)

3-5 Effective learning
To propose new learning methods; to be responsible for instructional content; to understand differences in learning needs among students. Teng (1995); Shih et al. (2011) 3-6 Group learning social skills To enable group members to communicate with each other in a friendly and respectful manner during group learning and develop interpersonal relationships and group skills. Huang and Lin (1996); Huang et al. (2011);Lai (2016) Quantitative Management Level (ML4) Developing capabilities of teaching resource management and effective assessment 4-1 Resource management capability To efficiently manage time and arrange teaching hours; to utilise various teaching resources and media; to efficiently manage teaching and learning portfolios. Pan et al. (2004); MOE (2016aMOE ( , 2018 4-2 Multiple assessment capability To conduct appropriate assessments based on teaching objectives and differences among students; to provide feedback and adjust teaching on the basis of assessment outcomes. Pan et al. (2004); MOE (2016aMOE ( , 2016bMOE ( , 2018 4-3 Curriculum and teaching evaluation capability To understand the fundamental concepts of curriculum and teaching evaluation; to select and evaluate textbooks; to plan and implement teaching evaluations; to improve teaching quality on the basis of the curriculum and teaching evaluations. Pan et al. (2004) 4-4 Group learning processes To self-reflect and improvement on the basis of group activity processes; to improve group learning effectiveness. Huang and Lin (1996); Huang et al. (2011);Lai (2016) Sustainable Optimisation Developing a positive professional attitude and continuing innovation and learning 5-1 Professional responsibility To be mindful of and comply with teaching ethics and related laws and regulations; to be enthusiastic about education; to care about students' rights to education and development; to actively participate in school affairs and development. Pan et al. (2004); Wu (2010); MOE (2016aMOE ( , 2018 5-2 Professional development To be aware of the role of teachers as professionals; to be willing to learn and explore new educational concepts; to participate in teacher training and a professional learning community; to plan professional development. Pan et al. (2004); MOE (2016aMOE ( , 2016bMOE ( , 2018

5-3 Research innovation
To employ various instructional methods to improve teaching; to share research findings; to collaborate with others to conduct research and develop professionalism. MOE (2016aMOE ( , 2016bMOE ( , 2018 5-4 Creative learning To enjoy discussing ideas during the learning process and generate solutions to complex problems; to enjoy contemplating educational strategies; to apply what has been learned to problem-solving tasks. Teng (1995); Shih et al. (2011) 5-5 Mutual and collaborative learning To ensure each student fulfils their responsibilities in group learning; to achieve optimal performance; to cooperate to complete tasks and master subjects. Huang and Lin (1996) (Table 2). This study also referred to Teng (1995) and the self-oriented learning tendency scale developed by Shih et al. (2011) to develop the 'active learning capability' component. The 'problem-solving capability' component was included in the model on the basis of the collaborative learning-related studies of Huang and Lin (1996), Huang et al. (2011), andLai (2016).
Advanced course management implementation (ML3  (2016) were referenced for the 'mutual and collaborative learning' component.

Research method
To construct a maturity model to assess the capabilities of CLIL teachers, a multistage method was adopted for data collection. First, an initial indicator framework was created through a literature review, after which expert opinions were collected using the MDM. The results were used to create a questionnaire based on fuzzy hierarchical analysis. The weight of the components in each level was calculated to construct a weighting system.
Participants. Representative experts from their respective groups were invited to participate in this study. Experts with professional knowledge and work experience have a comprehensive understanding of their field, which facilitates decision-making; accordingly, the Delphi method was adopted. In cases of experts with similar expertise, a group of 5-10 experts is sufficient for the Delphi method. However, a group of 15-30 experts is preferable for experts with highly homogenous expertise (Delbecq et al., 1975;Lin, 1992). Dalkey (1969) noted that group error is lower and credibility is higher when a Delphi panel consists of at least 10 members. The participants in this study responded to questionnaires designed using the MDM and fuzzy hierarchical analysis. Because the respondents determine the success of research, the representative experts and scholars were carefully selected to ensure the reliability of their expertise and practical knowledge and to ultimately achieve the research objective. Purposive sampling was employed to recruit a total of 33 experts, comprising interdisciplinary professionals in English teacher training institutions, primary school English teachers, and preservice English teachers. The participants' professional knowledge and experience in their respective educational institutions generated a diversity of opinions regarding English teacher training, which contributed to the construction of a maturity model for English teachers' teaching capabilities.
The survey was conducted in two stages. The first stage involved the administration of the modified Delphi expert questionnaire. The experts were invited to participate in the study by phone and email and required to complete paper-based or web-based questionnaires, which were then collected anonymously. A total of 33 questionnaires were distributed, and 33 valid questionnaires were collected, yielding a response rate of 100%. The second stage involved the administration of a questionnaire based on fuzzy hierarchical analysis, and the experts and scholars from the first stage were asked to complete the questionnaire. As in the first stage, a total of 33 questionnaires were distributed, and 33 valid questionnaires were collected.
The opinions of the 33 experts were compiled and reviewed. The experts comprised 18 primary school teachers, 8 university professors, and 7 preservice teachers. Of the 33 participants, 71.88% had a postgraduate education level or higher, indicating that the experts had a professional background related to higher education and possessed a wealth of experience in teaching practice. Therefore, they also had a deep understanding of professional literacy in the field of English teacher training. Table 3 presents the background information of the experts. their knowledge, provide comments, and speculate on the basis of their experience until they reach a consensus. This method is useful for effectively predicting trends, generating solutions, and solving problems (Murry and Hammons, 1995).

Research instruments
The MDM is based on the Delphi method. Its implementation and statistical methods are similar to those of the Delphi method, but the complicated questionnaire-answering procedure is simplified to expedite the experimental process, increase the response rate, and rapidly obtain a consensus among the panel members. As an improvement to the Delphi method, the MDM uses highly credible hypotheses based on the literature and the researchers and experts' experience in certain research topics.
The MDM questionnaire was administered during the first stage of the survey. A 5-level 25-component framework was established for the maturity model. The questionnaire had a semistructured design for the components of the framework. Each item in the questionnaire was a multiple-choice question, and the appropriateness of the component was evaluated using a 5-point Likert scale, with 1 representing strongly disagree and 5 denoting strongly agree. The experts were asked to review the definitions of the components in each level and assess the appropriateness of their classification and content. If the experts had any suggestions for amendments or additions to the components, they were asked to provide them in the comment columns to serve as a basis for revisions.
Fuzzy hierarchical analysis questionnaire. The fuzzy hierarchical analysis process (FAHP) is a decision-making method that integrates the analytical hierarchy procedure and fuzzy theory. The fuzzy weight of each element is calculated by forming a pairwise comparison matrix using symmetric triangular fuzzy numbers. The FAHP uses the fuzzy concept to resolve problems associated with typical human thinking, including subjectivity, uncertainty, and fuzziness (Hwang et al., 2008). This study used the FAHP to analyse and process the evaluation criteria for an employee assistance programme to establish a credible, objective, and quantitative index system.
The first step was to identify the elements and establish the initial hierarchical relationship. On the basis of the evaluation scale, the criteria were compared in pairs to form a pairwise matrix. Subsequently, a consistency test, defuzzification, and normalisation were performed to rank the evaluation elements on the basis of their importance, thereby generating a weighting system for the indicators.
The fuzzy hierarchical analysis questionnaire in the second stage of this study was based on the experts' opinions from the MDM questionnaire in the first stage. The questionnaire items were rated in terms of the importance of the levels and components. The evaluation was conducted through a pairwise comparison in which the relative importance of the left and right components was compared. The importance was expressed using a scale value of 1-9 points, with 1, 3, 5, 7, and 9 points representing equally important, slightly important, important, very important, and absolutely important, respectively. Higher scores indicated a higher level of importance. The experts were asked to assign relative importance by selecting a score between 1 and 9 points on the basis of their professional knowledge.
Research results MDM analysis. In this study, teachers, experts, and scholars in the field of English teacher education and training were invited to complete questionnaires in two stages. The questionnaire data collected from these two stages were reviewed and input into Microsoft Excel for data construction and analysis. During the first stage, the experts only made minor corrections to the text, which did not affect the overall framework of the maturity model for CLIL teacher training. The fuzzy hierarchical analysis in the second stage was performed to determine whether the overall hierarchical structure was consistent. After the questionnaires were collected, the consistency indicator and consistency ratio were calculated to ensure the evaluation results passed the consistency test.
After the MDM questionnaires were collected and filed, the means, standard deviations, and quartile deviations of the appropriateness of each component according to the experts were calculated to serve as the basis for the questionnaire design in the second stage. In accordance with the standards for evaluating the consistency of expert opinions proposed by Faherty (1979), quartile deviations of Q ≤ 0.6, 0.6 < Q ≤ 1.0, and Q > 1.0 indicate high, medium, and low consistency among the experts' opinions regarding the questionnaire items, respectively. The questionnaire analysis yielded a quartile deviation of less than 0.6, indicating a high level of consistency among the participants' opinions regarding the appropriateness of the components. The standard deviations of the closed-ended questions were <1, indicating high consistency among the experts' opinions. The questionnaire for the fuzzy hierarchical analysis in the second stage was designed on the basis of the results of the MDM questionnaires. Table 4 presents the results of the survey for each level.
The analysis results of the first-stage modified Delphi expert questionnaire confirmed the 5 MLs and 25 elements regarding the architecture of teaching abilities of English student teachers. The architecture was employed to devise the second stage of the (FAHP) questionnaire. The experts were asked to evaluate the importance of each level and the elements in each level. The questionnaire was evaluated using a 9-point interval scale with anchors of identically important, slightly important, important, very important, and absolutely important. Importance was assigned a value of 1-9 points; a larger value indicated a higher level of importance. The questionnaire results were ranked in terms of relative importance using the FAHP. The weight of each level was analysed to establish a weighting system for the elements.
Fuzzy hierarchical analysis. The survey data from the fuzzy hierarchical analysis questionnaires revealed the experts' and scholars' opinions regarding the evaluation indicators of the model. The results indicated the weight and priority of each level and component. Table 5 presents the indicator structure and weight ranking.
The consistency indicator (CI) and consistency ratio (CR) of ML1-ML5 were 0.01 and 0.01, respectively, both of which were <0.1, indicating that the experts' answers were consistent. In descending order of weight, the levels were basic course management level (0.28), advanced course management and implementation level (0.26), initial level (0.25), sustainable optimisation level (0.11), and quantitative management level (0.11). The initial level (ML1) consisted of five components: educational theoretical knowledge, educational contextual knowledge, theoretical knowledge of learner development, enjoying learning, and mutual dependency. The CI and CR of this level were 0.05 and 0.04, respectively, both of which were <0.1, indicating that the experts' answers were consistent. In descending order of weight, the components were educational contextual knowledge (0.28), theoretical knowledge of learner development (0.24), educational theoretical knowledge (0.21), enjoying learning (0.16), and mutual dependency (0.11).
The basic course management level (ML2) also comprised five components, namely content knowledge, content pedagogical knowledge, curriculum development capability, active learning capability, and problem-solving capability. The CI and CR of this level were 0.02 and 0.01, respectively, both of which were <0.1, indicating that the experts' opinions were consistent. In descending order of weight, the components were content knowledge (0.23), curriculum development capability (0.22), content pedagogical knowledge (0.21), active learning capability (0.20), and problem-solving capability (0.15).
The advanced course management and implementation level (ML3) consisted of six components: content teaching capability, classroom management capability, student counselling capability, communication coordination capability, effective learning, and group learning social skills. The CI and CR of this level were 0.01 and 0.01, respectively, both of which were <0.1, indicating that the experts' answers were consistent. In descending order of weight, the components were content teaching capability (0.32), classroom management capability (0.19), student counselling capability (0.15), group learning social skills (0.13), communication coordination skills (0.11), and effective learning (0.11).
The quantitative management level (ML4) consisted of four components: resource management capability, multiple assessment capability, curriculum and teaching evaluation capability, and group learning processes. The CI and CR of this level were 0.05 and 0.05, respectively, both of which were <0.1, indicating that the experts' opinions were consistent. In descending order of weight, the components were multiple assessment capability (0.46), resource management capability (0.23), curriculum and teaching evaluation capability (0.18), and group learning processes (0.13).
The sustainable optimisation level (ML5) consisted of five components, namely professional responsibility, professional development, research innovation, creative learning, and mutual and collaborative learning. The CI and CR of this level were both 0.00, which was <0.1, indicating that the experts' answers were consistent. In descending order of weight, the components were professional responsibility (0.29), professional development (0.27), creative learning (0.16), research innovation (0.16), and mutual and collaborative learning (0.12).

Discussion
According to the participants, the three most important levels were basic course management (ML2; weight = 0.28), advanced course management and implementation (ML3; weight = 0.26), and the initial level (ML1; weight = 0.26). The least important levels were quantitative management (ML4: weight = 0.11) and sustainable optimisation (ML5; weight = 0.11). The data analysis also revealed a marked difference in weighting between the most and the least important levels. Because CLIL is in the early stages of its implementation in Taiwan and because most of the teachers would be new to CLIL, the participants indicated that the teacher capabilities at the initial and fundamental levels in the maturity model were required for preservice teachers.
Although the quantitative management level (ML4) and sustainable optimisation level (ML5) ranked low, the multiple assessment   Pan et al., 2004;MOE, 2016aMOE, , 2016bMOE, , 2018, and content pedagogical knowledge (cf. MOE, 2016aMOE, , 2018 are integral to initial teacher education for CLIL (cf. Module 2 in Marsh et al., 2011). In a curriculum development course, preservice language teachers (i.e. preservice English teachers in Taiwan) can collaborate with preservice teachers of content subjects to develop a CLIL curriculum, thereby gaining the fundamental content knowledge required for curriculum design and strengthening their capability to develop CLIL curricula. Second, modules that provide preservice teachers with practical experience in teaching content subjects must be incorporated into the framework for CLIL teacher education. The results of this study indicated that the advanced course management and implementation level (ML3) was the second most important level. The participants indicated the high value of content teaching capabilities in this level. To enable teachers to successfully deliver CLIL instruction, CLIL teacher education must equip teachers with the competence of teaching content subjects (cf. Pan et al., 2004;MOE, 2016aMOE, , 2016bMOE, , 2018. In pedagogical CLIL courses, preservice teachers can understand effective practices in CLIL classes and adopt such practices in their teaching (cf. Module 1 in Marsh et al., 2011). In addition, preservice language teachers can collaborate with content subject teachers in teaching practicum courses. Through collaborative teaching with content subject teachers, preservice language teachers can gain hands-on experience in teaching content in another language.
Third, CLIL teachers should be equipped with knowledge of trends in education and multicultural issues related to the environment. This study demonstrated that the initial level (ML1) was the third most important level. The participants indicated that the most critical component in this level was educational contextual knowledge, which refers to knowledge of educational and multicultural issues related to curricula and teaching, schoolbased resources, and the influence of educational contexts on student learning (MOE, 2016a(MOE, , 2018. Modules that help CLIL teachers acquire such knowledge must be incorporated into the framework for CLIL teacher education and professional development. Preservice courses on teaching in multilingual and multicultural settings may help CLIL teachers understand educational and multicultural issues related to teaching and learning contexts. Fourth, subsequent studies of CLIL teacher education should investigate content teachers. This study investigated CLIL teacher education from the perspective of language teachers (i.e. preservice and in-service English teachers) and language teacher educators (i.e. university professors of English education). To explore various aspects of CLIL teacher education, the voices of language teachers and content teachers must be heard. Evidencebased research on CLIL teacher development from the perspective of teachers of various subjects should be conducted.
Limitations. The levels, dimensions, and indicators used in this study were adapted from a literature review. Although this study incorporated as many relevant factors as possible, examining all factors influencing professional literacy indicators of CLIL teachers is unfeasible. This study did not perform an in-depth analysis of all critical factors but only analysed selected indicators.
Data collection mainly involved reviewing the opinions of experts in the field rather than an analysis of a large amount of data obtained through conventional questionnaire methods. Thus, the conclusions may not be generalisable to other regions;

Conclusion
This study explored a TCMM for CLIL teachers. A questionnaire data analysis revealed high consistency among the participants' opinions regarding the appropriateness of the components in each level of the maturity model. In descending order, the most important levels were the basic course management level, advanced course management and implementation level, initial level, sustainable optimisation level, and quantitative management level. Although the scope of this study was limited to Taiwan, this study identified essential capabilities for CLIL teachers and demonstrated the importance of each level for those involved in the implementation of CLIL. Further research on the TCMM should be conducted with different cohorts (such as content teachers) to explore CLIL teacher development.

Data availability
The datasets generated during the current study are not publicly available but are available from the corresponding author on reasonable request.