Self-regulated learning (SRL) is crucial for fostering lifelong learning skills in students, encompassing planning, monitoring, and controlling abilities. Previous research indicates that many students struggle to regulate their learning effectively. In the Netherlands, adaptive learning technologies are widely used to support math education in primary schools, providing direct feedback and adjusting problem difficulty levels. Despite this, students still need to invest effort and monitor their progress, requiring better SRL skills. Previous research emphasized the importance of teachers' direct instruction of SRL strategies for primary school students. Yet, identifying classroom needs accurately and timely remains challenging, especially in large classrooms. Teacher dashboards provide a solution by aggregating, analyzing, and reporting students' learning processes through visualizations. However, existing SRL dashboards have not focused on enhancing direct strategy instruction and lack theoretical grounding. To address these gaps, we developed a theory-based teacher dashboard through iterative co-design. We conducted two rounds of interviews with primary school teachers to gather insights on their current SRL practices and refined prototypes. The first round of results (n = 10) informed the creation of low-fidelity prototypes. The second round of results (n = 11) showed that teachers found the low-fidelity prototypes actionable while they still required further improvement to ensure clarity. Importantly, these interviews underlined teachers' need for a dashboard to better support SRL in the classroom. This study outlines teachers' SRL practices and the initial design steps of a teacher dashboard, laying the groundwork for developing similar dashboards enhancing teachers' SRL practices and potentially improving students' self-regulation.