The semantics of programming languages comprise many concepts that are alternatives to each other, such as by-reference and by-value parameter passing. To help teach these concepts, Diwan et al. introduced the programming language Mystery, with fixed syntax but configurable semantics, and described how this language enables new approaches to teaching programming languages concepts. In this paper, we reproduce the studies by Diwan et al. in a [European Country] setting, describe extensions to the original system, and a new technique for evaluating the utility of student experiments. We largely confirm the earlier findings and show how our evaluation technique helps us in our understanding of student experiments.