This paper presents the usage of purposely adapted ECG interpretation software as a classroom tool providing reliable reference values of most diagnostic parameters for ECG records from any source. The software maintains the commercial reliability and no part of its source code is disclosed. Additional checkpoints and data switches between the internal procedures (e.g. beat detection, classification, typification etc.) allow for tracking the intermediate results or for using own input data with selected range of processing procedures. The data sources are thus not limited to the databases, but include also custom-recorded and modified signals. Students, usually making their projects concerning a specific task of ECG interpretation, have a reliable reference values and may quantitatively compare their achievments. The software is very helpful to the assistant-professor with only basic background from cardiology for supervising the students' project. Our approach may also be beneficial to the manufacturer, since the statistics show that outcomes of some best students are increasingly competitive.