Formal methods have always been controversial. In spite of the fact that the disbelief about their usefulness has been corrected by a growing number of applications and even more publications, it remains a challenge to demonstrate the strengths and weaknesses of formal methods within the time constraints of a typical semester course. This article 1 This article is an extension of a paper that has been elected the best paper at the Educators’ Symposium at the 9th ACM/IEEE international conference on model-driven engineering languages and systems (MODELS) held in 2007 in Nashville, USA. 1 reports on a new course at the University of Antwerp in which the introduction of a new formalism yields a better understanding of previously taught ones. While the exercises are designed to reveal the limitations of the formalisms used, students remain convinced that their formal models have more value than conventional source code.