Cleveland State University (CSU) in collaboration with the University of California San Diego (UCSD), proposes CISS -- Computing in Secondary Schools -- a CS10K project designed to provide computer science education professional development to high school teachers throughout the state of Ohio. Through participation in CISS, high school teachers will become fluent in computational thinking and will develop the skills needed to teach the new AP CS Principles course. The teachers will be supported through access to course materials, pedagogy, mentoring, weekly telephone meetings, mid-year workshops and technical coaches. Teachers will also have access to an online knowledge repository, CS Learning Commons, which will be used to address challenges that arise and share best practices. Specifically the project will (1) recruit, train, and assist 30 high school teachers in teaching CS in their classroom; (2) prepare and teach an open online course focused on CS education, which will include both content knowledge required to teach CS at the high school level as well as the pertinent pedagogical techniques; (3) widen the CS teacher pipeline by offering a teacher licensure pathway; (4) create a replicable network design model for CS teacher training and mentoring by engaging with an online school network; and (5) establish CS mentoring programs for high school teachers with a focus on gender diversification and participation by minority teachers. Additional partners include the Ohio STEM Learning Network (OSLN) and school districts geographically dispersed throughout the state of Ohio. This project will leverage the work already done on ComPASS CS 10K award and will increase our understanding of its scaling to a wider audience.