Standardized teacher professional development (STPD) refers to centralized approaches like workshops, trainings and seminars. STPD focuses on exploring new concepts through demonstrations and modeling skills using visual, auditory and tactile techniques. STPD relies heavily on training-based approaches where presenters share skills with large groups. Other models of STPD include the cascade model where champion teachers train colleagues, and site-based training where teachers work with local facilitators. Self-directed STPD allows teachers to determine their own goals and select activities.