Teaching observation protocols serve purposes beyond research, such as providing formative feedback for teachers' growth in their practice. Such observation tool usage requires different approaches for validation. For this reason, we developed the formative teaching evaluation framework adapted from the student-assessment literature. We used this framework as a guide toward collecting and organizing evidence of practitioners using the Math Habits Tool as a means for formative assessment of teaching. This report focuses on how we designed surveys and interviews to collect validity evidence related to the formative teaching evaluation intentions of the MHT. Overall, we established that the MHT was being used as intended by teachers and school leaders, and we provide details about the development and analysis procedures we took toward validating this observation tool for practitioner use. [For the complete proceedings, see ED657822.]