The collaboration of teachers is a tool for their continuous professional development, and changes in initial vocational education and training (Cedefop, 2023) call for the need to research focus on how vocational teachers cope with new challenges and requirements for the quality of their pedagogical work. The collaboration of vocational teacher (teachers of vocational theoretical subjects and teacher of practical subjects) in IVET schools  among themselves, within the school where they work, or the collaboration of vocational teachers with employers are possible ways in which teachers develop their skills and competences, they cope with some structural changes (Cedefop, 2022; Sirk, Liivik, & Loogma, 2026), change their pedagogical or instructional practices, their beliefs, attitudes and their students achieve better learning outcomes (Guskey, 2002).

Empirical researches quite well give proof of the degree and form of collaboration of vocational teachers changes over time (Bükki & Fehérvári, 2021; Sirk, Liivik, & Loogma, 2016). Empirically verified models of professional development of teachers (Haberman, 1989,1995; Lukas, 2011) and professional life phases (Day, 2012) led us to assumption, that the perception of vocational teacher collaboration to the improvement of the pedagogical process is different in the length of teaching practice. These assumptions directed us to the following research questions:

RQ1: How do vocational teachers evaluate the collaboration between themselves and with the school management to improve the quality of the educational process in 2016/2017 and in 2022/2023?

RQ2: How do vocational teachers evaluate the expression of disapproval of the steps taken by the management and fellow teachers in 2016/2017 and in 2022/2023?

RO3: How do vocational teachers perceive the suggestions from students to the improvement of the educational process in 2016/2017 and in 2022/2023?

RQ4: In which professional life phase (Day, 2012) do vocational teachers best evaluate the collaboration between themselves and with the school management to improve the quality of the pedagogical process?

RQ5. At what professional life phase (Day, 2012) do vocational teachers perceive positively the suggestions from the students to improve the quality of the pedagogical process?

As part of the research investigation, data from the Czech School Inspectorate (CSI) was used, which contains answers to questions posed to secondary school teachers (general and technical/vocational) through an electronic questionnaire during inspection activities in schools. Teachers' answers serve as additional information to the inspection findings obtained from visits, analysis of school documentation and other sources. From the two datasets obtained in the school year 2016/2017 and 2022/2023, the responses of teachers who indicated that they teach a vocational theoretical subject and/or practical subjects for ISCED 3 were selected. For the year 2016/2017, there were 1,418 teachers from 181 VET schools – 43.9% of respondents of the total set. In 2022/2023, there were 1,879 respondents from 200 VET schools - 38.5% of respondents of the total set. As a main tool for the secondary analysis, we used a free version of the JAMOVI software and IBM SPSS Statistics ver. 24. Firstly we created six categories of teachers (0-3; 4-7; 8-15; 16-23, 24-30, more 31 years) inspired by Day (2012) from open questions on length of teaching experience in all two data sets. Secondly, in accordance with the research questions, attention was focused on 12 items related to the perception of cooperation of school management, teachers and students. Exploratory factor analysis was used for these items. Extraction (principal component analysis; Varimax with Kaiser normalization) found three factors that represent 61.5% of the total variance extracted. Based on them, we created indexes from several CSI questionnaire items. The number of items, Cronbach's alpha and polarity of index in the order 2016/2017, and 2022/2023 are given in parentheses: "Index of collaboration between teachers and management leading to the improvement of the educational process" (8, 0.87; 8, 0.86; 1:best – 4: worst); "Index expression of disapproval of the steps taken by the management and fellow teachers" (2, 0.63; 2, 0.63; 1: most disapproval – 4: least disapproval); "Index of perception of students' initiatives to improve the quality of the educational process" (2, 0.75; 2, 0.69; 1: most initiatives - 4: least initiatives).

The collaboration of vocational teachers changes over the years and during their professional career. Vocational teachers evaluate the collaboration with the school management and with each other to improve the quality of the educational process in the same way in 2016/2017 and in 2022/2023 (RQ1; mean 2016/2017: 1.70; mean 2022/2023: 1.69). Vocational teachers express differently in 2016/2017 and 2022/2023 their disapproval of the actions of the management and fellow teachers (RQ2) and they perceive suggestions from students to improve the quality of the educational process (RQ3). In 2022/2023, they express of disapproval of the steps taken by the management's actions more (means: 1.93 < 2.36) and better accept initiatives to improve the quality of educational process from the students (means: 2.05 < 2.57) than in 2016/2017. The collaboration between teachers and management leading to improve the quality of the educational process is best evaluated by vocational teachers in the years 2016/2017 and 2022/2023 at the end of their career (31 or more years of experience; see Lazarová et al. 2011), when they are in the phase of maintaining/declining motivation, have the ability to cope with changes, retire and, based on their experiences, are reconciled to the reality of their work and interpersonal relationships (RQ4). In 2016/2017 and 2022/2023, vocational teachers positively perceive students' suggestions to improve the quality of the educational process when they are at the beginning of their career (0-3 years of experience), when they are engaged, close in age to their students and open to their suggestions (RQ5).

Bükki, E., & Fehérvári, A. (2021). How do teachers collaborate in Hungarian VET schools? A quantitative study of forms, perceptions of impact and related individual and organisational factors. Empirical Research in Vocational Education and Training, 13(2), https://doi.org/10.1186/s40461-020-00108-6 Cedefop. (2023). The future of vocational education and training in Europe: synthesis report. Luxembourg: Publications Office. Cedefop reference series; No 125. http://data.europa. eu/doi/10.2801/08824 Cedefop. (2022). Teachers and trainers in a changing world: building up competences for inclusive, green and digitalised vocational education and training (VET): synthesis report. Luxembourg: Publications Office. Cedefop research paper, No 86. http://data.europa.eu/doi/10.2801/53769 Day, C. (2012). The New Lives of Teachers. Teacher Education Quarterly, 39(1), 7–26. https://files.eric.ed.gov/fulltext/EJ977354.pdf Guskey, T. R. (2002). Professional Development and Teacher Change. Teachers and Teaching: theory and practice, 8(3/4) 381–391. https://doi.org/10.1080/135406002100000512 Huberman, M. (1995). Networks that alter teaching. Teachers and Teaching: conceptualizations, exchanges and experiments. Theory and Practice, 1(2), 193–211. https://doi.org/10.1080/1354060950010204 Huberman, M. (1989). The Professional Life Cycle of Teachers. Teacher College Records, 91(1), 31–57. https://doi.org/10.1177/016146818909100107 Lazarová, B. et al. (2011). Pozdní sběr. O práci zkušených učitelů. [Late harvest. About the work of experienced teachers.] Paido. Lukas, J. (2011). Vývoj a kariéra učitele. In B. Lazarová. Pozdní sběr. O práci zkušených učitelů. [Teacher development and career. In B. Lazarová. Late harvest. About the work of experienced teachers.] Paido. Sirk, M., Liivik, R., & Loogma, K. (2016). Changes in the professionality of vocational teachers as viewed through the experiences of long-serving vocational teachers in Estronia. Empirical Research in Vocational Education and Training, 8(13), https://doi.org/10.1186/s40461-016-0039-7 The analysis was created as part of the activities of the ERASMUS-EDU-2021-EQAVET-IBA project, No. 101048408 entitled "Support for quality assurance in VET".