This study highlights important aspects of the transition from face-to-face to emergency remote teaching (ERT) in the context of elementary school mathematics. The integration of computerised technologies in teaching is a process that requires a change in teaching method and sometimes in teachers’ worldview as well. The research examined the level of technology integration in mathematics lessons using the five-step Apple Classrooms of Tomorrow model. The relationship between mathematics teachers’ teaching strategies and their perceptions of their role in the classroom and in remote teaching in an emergency was analysed. The teachers’ level of comfort with technology integration in face-to-face teaching was found to strongly impact their perceptions of online teaching and the strategies used when transitioning to ERT. We point out tools that teachers need, and that they often lack, in order to incorporate teaching strategies at high levels of thinking, such as research-based learning, problem-solving, and developing classroom discussions while working in collaborative groups, into an online format. Implications arising from this study can shed light on the emphasis that must be considered when planning courses that prepare teachers for ERT, whether for in-service teacher training or bachelor’s and master’s degree programmes.