Abstract
This study reports the development and piloting of the Responsive Mathematics Teaching Observation Scale (RMTOS), a structured classroom observation instrument designed to capture teachers’ responsiveness to students’ mathematical thinking. We trialled the instrument across 24 mathematics lessons observed twice weekly over six weeks across two Year 6 classrooms in a public primary school. The findings provide preliminary evidence that responsive mathematics teaching can be operationalised through structured observation, and the refined instrument offers a promising tool for future research on mathematics instruction and teacher professional development.