This Targeted Research project is investigating the impact of an approach to K-12 professional development for mathematics teachers that rests on the explicit cultivation of teacher creativity in producing short explanatory videos to help engage students in learning mathematics concepts. All videos are reusable and shareable using NSDL-compliant standards so that they may accumulate over time into substantial and sharable personal resource collections. Underlying this research is an emerging theory of personalized learning communities and pilot work carried out with support from NSF's Computer and Information Science and Engineering Directorate and the Department of Education's Institute for Education Sciences. Target audiences for this research include middle and high school mathematics teachers, undergraduate teacher education and mathematics faculty; members of various learning science, mathematics education, policy and creativity research communities; and individuals in professional development policy and decision-making roles. The project's intellectual merit stems from its underlying theory base involving prior research in classroom dynamics, current pilot work on the integration of digital library resources with teacher professional development, and a methodical approach to research on digital library impact. The project is exerting broader impacts by contributing creativity-centric approaches to teacher participation in resource collection adaptation and generation to NSDL and to the usability of certain types of resource libraries. Additionally, this impact extends to its potential influence on pre-service teacher education in undergraduate mathematics departments.