Mathematical manipulative materials (manipulatives) invite students to explore and represent abstract mathematical concepts in varied, concrete, tactile, and visually rich ways. Considering the prominence of the use of mathematical manipulatives in current K-12 curricula, pedagogical resources and professional development, research studies show that few secondary school teachers use them. While these studies do not examine this issue from the teachers perspective, they posit that some teachers lack the mathematical knowledge connected to manipulatives, are uncomfortable with or uncertain how...