<p>In this research, we investigated learning during online in-service training for teachers of mathematics. It is recognised that the need to develop professional knowledge and skills continues throughout one’s career, and this is highly applicable to the teaching profession. In the study, we applied the Meaningful Learning model as a theoretical lens. Data were collected through questionnaires completed three times (first time measuring expectations, after that experiences) during the in-service training course. A total of 589 responses from teachers teaching at several levels of education were received. Data were analysed with exploratory factor analysis, <i>t</i>-test, an Analysis of Variance (ANOVA), and hierarchical cluster analysis. Based on the results, the meaningfulness of learning is mainly experienced as satisfaction with learning and professional and goal orientation in learning. There was a drop in both after the initial measurement point targeting expectations. Teachers’ satisfaction with learning decreased over the measurement points. Their experiences of professional and goal orientation in learning stayed relatively stable during the second and third measurement point. It is possible that the participants experienced challenges with the interaction online, but nevertheless experienced it as supporting them professionally. Understanding learning expectations and experiences may support the development of online in-service training to better align with needs of mathematics teachers. In further development of the theoretical model, we propose satisfaction and professional and goal orientation in learning as two overarching denotations of meaningful learning in the context of in-service teacher training.</p>