This chapter focuses on developing and using models. In each chapter, the practice is dissected into distinct and clear learning tasks that serve as process goals for learning the practice. These tasks are then examined within the context of a self-regulated learning cycle and coaching strategies for instruction and assessment are emphasized. The instruction and assessment strategies are contextualized for students in grades 9–12 and focus on developing and refining a model for electrolysis. The tasks are reassembled into two case studies – one positive and one negative – to demonstrate how the learning tasks can be used by students and how teachers can support students learning how to develop and use models.