In a constantly changing society, continuous professional development and further education is essential for teachers (Messner & Reusser, 2000; Fabel-Lamla, 2018). This demand for continuous development as well as for further training courses that meet teachers' specific needs, fit into their busy schedules and provide high quality learning opportunities have encouraged the creation of online teacher professional development (oTPD) programmes. OTPD includes various formats such as multimedia websites or online courses, and both synchronous and asynchronous approaches are possible (Morina et al., 2025). Such online programmes offer a number of benefits, including flexibility, improved access and lower costs for participants (Lay et al., 2020; Morina et al., 2025). Moreover, research has shown that learners generally master the course material just as well in online courses as in on-site courses (Fisher, et al., 2010; Fishman, et al., 2013). However, there is some evidence that learner characteristics seem to influence the online learning experience. For example, learners' prior knowledge of technology and self-regulation skills have been found to affect learning outcomes in online courses (Jung & Rha, 2000). Also, motivational and volitional issues can emerge because participants may feel less socially integrated in purely online courses. On the other hand, positive self-regulation or intrinsic motivation can contribute to learning success in online learning (Dede et al., 2009; Justus, 2017).

Studies to date show that online courses should increasingly focus on materials and tangible skills that teachers can use in the classroom (Morina et al., 2025). Also, it has been demonstrated that teachers' voices are largely absent. As a result, there is a limited understanding of the perception of oTPD courses and best practice regarding the design and implementation of such courses (Dede et al., 2009; Powell & Bodur, 2019).

Against this background, 30 oTPD courses were co-constructively created by a lecturer of a university of teacher education and a mentor teacher for different school levels (kindergarten, primary school level, secondary school level) and different subjects (e.g. first language, foreign language, mathematics, history, music, sports). The oTPD courses were designed for teachers and mentor teachers, who comprehensively evaluated the courses after their completion. A mixed methods design was employed to gain insights into teachers’ expectations of the oTPD courses, their overall satisfaction, and their rating of the success of the oTPD courses. The present paper explores the evaluation provided by the teachers and mentor teachers, with a particular focus on the following research questions:

1. How well are the teachers’ expectations of the learning opportunities provided by the oTPD courses being met, and how satisfied are they with the oTPD courses overall?
2. Are there differences in the ratings of the success of the oTPD courses (i.e. acceptance, knowledge acquisition, usefulness for teaching, usefulness for mentoring) in relation to the teachers‘ characteristics (i.e. general teacher self-efficacy, self-regulation, digital skills, gender)?
3. How does the perceived quality of the oTPD courses relate to the teachers’ assessment of the success of the oTPD courses?

The 30 oTPD courses were completed and evaluated by 183 teachers and mentor teachers. Their responses were collected through an online questionnaire. The survey was carried out between December 2023 and March 2024 and included three measurement points: the first was before starting the course (T1), the second immediately after completing the course (T2), and the third four to six weeks after completing the course (T3). This approach allowed for the collection of information regarding participants' preconditions, previous experiences and expectations (T1), their perceptions of the courses (T2) and the benefits for their teaching practice and mentoring (T3). The questionnaires were designed based on established instruments and scales. The expectations regarding the learning opportunities and overall satisfaction with the oTPD courses (research question 1) were assessed with items adapted from Burghard (2008) and self-created items. Success of the oTPD courses (research questions 2 and 3) was measured across four dimensions: acceptance (items adapted from Bürg et al., 2005), knowledge acquisition (items adapted from Heran-Dörr, 2006), perceived usefulness for one’s own teaching (items adapted from Bachmeier, 2011), perceived usefulness for mentoring students (items adapted from Gröschner & Häusler, 2014). As preconditions (i.e. teacher characteristics, research question 2) general teacher self-efficacy (adapted from Schmitz & Schwarzer, 2000), self-regulation (adapted from Chrobak, 2004), and digital skills (adapted from Zahn et al., 2019) were assessed. All answers were given on a 5-point Likert scale. The perceived quality of the online courses (research question 3) was assessed across subscales including practical relevance, sustainability of learning outcomes, cognitive activation, transfer work and scientific relevance (Rezjak et al., 2023) with answers given on a 6-point Likert scale. The data were evaluated using regression analyses in the SPSS statistical software, with the different quality factors serving as predictors of the success of the oTPD courses (i.e. 4 dimensions). Note: References to the questionnaire instruments used are not included in the 'References' section due to word limits.

Regarding research question 1, over 72% of the participants indicated that their expectations of the oTPD courses had been met overall (those provided item ratings of 4 or 5; M=3.77, SD=0.99). Overall, at T3, the participants were very satisfied (M=3.88, SD=0.95) and would recommend the oTPD courses to colleagues (M=4.10, SD=0.91). For research question 2, higher self-regulation skills correlated with higher values on acceptance of the online courses (r=.163), perceived usefulness for one’s own teaching (r=.172), and higher overall satisfaction with the online courses at T3 (r=.177, p <.05). Female participants rated the courses more favorably than males (p=.049, d=.898). No correlation was found between digital skills as well as general teacher self-efficacy and the success of the oTPD courses. Regarding research question 3, regression analyses were conducted with the different factors of quality as predictors of the success of the oTPD courses (i.e. four dimensions). These analyses showed that practical relevance was the most significant factor for the success of the oTPD courses. It showed significant correlations with acceptance (r=.654, p<.001), knowledge acquisition (r=.473, p<.001), perceived usefulness for one’s own teaching (r=.584, p<.01), and perceived usefulness for mentoring (r=.448, p<.05). The study shows that online courses can contribute to teachers' professional development. However, not all teachers can benefit equally from the oTPD courses. Teachers with high self-regulation skills may benefit more than those with lower self-regulation skills. Furthermore, the quality of the course material, particularly its practical relevance, is very important for the success of such courses, which argues for collaboration between academic and school-based course creators, as was the case in our study. The findings can lead to a better understanding of the requirements for oTPD courses, guiding future design and implementation, ensuring that both teachers and mentor teachers can derive even greater benefit from these courses.

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