External assessments may be applied to a full student cohort or only in some schools and classrooms (for example, on-demand assessments that schools can use to measure their own progress and benchmark themselves against national averages). For example, there are also hybrid forms of assessment that are developed externally but implemented and marked internally by the students’ own teachers. How to best design assessment frameworks drawing on a mix of internal and external approaches in order to achieve stated summative and formative purposes will be another guiding question throughout this chapter. These terms are briefly defined below, as they will be used frequently throughout the chapter.