This study examines changes in middle school mathematics teachers’ teaching methods and materials during the transition from face-to-face to online education and difficulties in terms of teaching methods and materials used in this process. 35 middle school mathematics teachers’ lesson plans for both face-to-face and online classrooms were analyzed according to their content, and the reason for the changes in teaching practices of the teachers was evaluated through interviews. While the study revealed that the use of lecture-based and demo & practice methods increased with the transition from face-to-face education to online education, teachers stated that they did not use different teaching methods in the classroom. It has been determined that the situations that limit the use of different teaching methods are the low motivation of the students and the difficulties of the teachers in the classroom management process. In addition, the use of concrete manipulatives has been replaced by videos and other digital teaching tools in online education. Other reflections of compulsory transitions to online education on teaching practice were discussed in terms of teaching the subject of probability and within the framework of in-service teachers' training.