Abstract: The ASSET program is designed to leverage principles of learning sciences to deliver professional development for teachers through online, self-paced, competency-based education (CBE) micro-credentials that include simulated learning environments. The goal is to increase the number of highly effective educators in K-12 high-need schools in rural Appalachia. In this session, our team will share our emerging understanding of the complexities of working with simulated learning environments. We will share tips and strategies for working with vendors at all stages of the design process as well as our lessons learned.