We know that Professional Development (PD) in the Top Performing Countries is CENTRAL to their jobs. It is not an add-on. It is not something done on a Friday afternoon or on a few days at the end of the school year. Teacher professional learning is how they all improve student learning; it is how they improve schools, and it is how they are evaluated in their jobs. They work in systems that are organized around improvement strategies explicitly anchored in teacher professional learning. (from Jensen, Sonnemann, Roberts-Hull, & Hunter, 2016).