Professional Development (PD) can be defined as teachers’ ongoing learning to improve the way they teach. Professional development sessions usually feature a combination of presentations, hands-on workshops, and collaborative teamwork that are often organized in advance by school and school district leadership. Additionally, teachers also set their own, informal, ongoing PD agendas, such as taking additional courses, pursuing graduate study, personal study of their subject matter or teaching approaches, sharing resources and ideas with colleagues, and building learning networks through social media.