Simplified Entity relationship UML diagram. A simple UML diagram that specifies relationships between the main application objects. Multiple Notebooks belong to a Group, and multiple Groups belong to an institution. An institution has multiple topics and Flashcards. A Notebook may hold multiple topics that are associated to multiple Flashcards. Multiple topics can also belong to a broader topic. A Flashcard can be composed of one or two facts, up to two description items, up to four images and one to eight questions. Multiple questions can be associated to a Fact, Description or Image.