Petri nets are commonly used in various applications, such as software engineering or business process modeling. Naturally, new personnel in these fields need to acquire knowledge about Petri net semantics to use them effectively. Traditional teaching strategies rely on static, non-interactive exercises that require manual preparation and assessment. Although there are tools available to quickly construct Petri nets, none of them focuses specifically on creating and grading exercises. In this paper, we thus present Petri-Dish, an editor for Petri net exercises and case studies. For teaching personnel, this tool offers quick creation of questionnaires and automatic assessment. By providing basic metrics for the constructed Petri nets, it enables its users to prepare exercises in the desired complexity with low effort. Furthermore, Petri-Dish provides an overview of all students’ solutions, thus highlighting which topics were not yet well understood. For students, the tool provides an interactive interface that allows free rearrangement of model elements. These features also enable users to easily execute case studies, as demonstrated by two successful projects on Petri net understandability with Petri-Dish.