National audienceThis article is a presentation of the Cheddar toolset.Cheddar is a GPL open-source scheduling analysis tool.It has been designed and distributed to allow students to understand the main concepts of the real-time scheduling theory.The tool is built around a simplified ADL (Architecture Description Language)devoted to real-time scheduling theory. Students can directly build their real-time systems models with this ADL andits associated editor, however, it is expected that they use modeling tools to illustrate how scheduling analysis fits in an engineering process.In this article, we introduce the Cheddar ADL and the scheduling analysis features of Cheddar. We alsopresent how Cheddar is implemented and how it can be adapted to specific requirements.Two examples of use of Cheddar are then described.Finally, in the annex of this article, teachers may find a sample of hand-outs that may be used to illustrate real-time scheduling theory with their students