School-based citizen science (SBCS) provides opportunities for teachers to purposefully integrate mathematics and science content and practices throughout the year. With SBCS projects, students have countless opportunities to apply their mathematics skills within the context of science data collection and sense making. This article details how a group of researchers and educators designed a study to develop materials for two citizen science (CS) projects. Recruiting 50 teachers, this study focused on supporting teachers' incorporation of SBCS projects in their mathematics, science, literacy, and social studies teaching practices. The teachers provided feedback to inform the development and revision of the materials and to help the researchers understand how having written supports influences teachers' implementation of SBCS projects. One fifth-grade science and mathematics teacher in particular shares how she used the support materials to engage her students.