Abstract Understanding how mathematics teachers change after disruption is essential for supporting long-term professional growth. With the COVID-19 pandemic as a case, this longitudinal study examines how secondary mathematics teachers in Flanders, Germany, and the Netherlands responded over time to this disruption in terms of teaching practices, teachers’ beliefs, and assessment practices. To explore which changes persisted, which reverted, and how teachers reflected on their experiences, data were collected through two large-scale surveys, conducted in June 2020 and June 2021. A total of 2,058 teachers completed the follow-up questionnaire. Concerning teaching practices, we found a significant increase in videoconferencing and the use of homemade video clips. Learning management systems became a central part of teaching practice. However, there was little change in the use of online learning environments, exercise platforms, and digital mathematics tools. Regarding teachers’ beliefs, teachers reported improved digital skills, particularly with tools they used frequently, such as videoconferencing. However, they reported only slight changes in their perceptions of effective mathematics teaching and limited confidence in the use of digital formative assessment tools. Assessment practices shifted toward more interactive formats, including live questions and chat, while reliance on email declined. Our findings suggest that the impact of the crisis extended beyond the initial period of school closure and that the longer-term picture is more complex than early responses indicated.
Vandervieren et al. (2026) studied this question.