Professional learning is crucial for the ongoing development of teachers and the improvement of student outcomes. Professional learning in mathematics and science education has the potential to address concerns about shortages in these areas and their impact on economic growth. However, attendance at face-to-face professional learning is problematic for many teachers located in rural areas. This study explores the utilisation of online professional learning in mathematics and science education by teachers in rural areas, and canvasses teachers' requirements for this form of professional learning. An activity system, using cultural-historical activity theory, is developed for online professional learning for teachers of mathematics and/or science. Qualitative interpretive analysis of transcripts of 14 semi-structured individual interviews with three different groups of people suggests that teachers of mathematics/science require professional learning programs which are not only flexibly delivered but also provide professional learning content that has high utility value. By better understanding how teachers respond to the notion and practice of online professional learning, informed decisions can be made about how best to support teachers and thus build capacity in schools for success in mathematics and science.