Abstract Debugging skill is an essential part of the programming skills. It is also highly related with program comprehension skills. In this paper we present a novel tool, called ViLLE, which supports learning debugging by promoting students' understanding of target program. ViLLE combines visual debugging features with the support for roles of variables. These roles promote activating schemas of variable use in programs. In addition, ViLLE supports automatic presentation of the target program in different programming languages, even in pseudo code or with textual explanations. This, in turn, helps in building more general and abstract understanding of program structures and their relation to problem domain concepts. The key features of the tool are