In this article we present an educational approach to thermal equilibrium which was tested on a
group of 13 undergraduate students at the University of Trento. The approach is based on a
stochastic toy model, in which bodies in thermal contact are represented by rows of squares on a
cardboard table, which exchange coins placed on the squares based on the roll of two dice. The
discussion of several physical principles, such as the exponential approach to equilibrium, the
determination of the equilibrium temperature, and the interpretation of the equilibrium state as the
most probable macrostate, proceeds through a continual comparison between the outcomes obtained with
the toy model and the results of a real experiment on the thermal contact of two masses of water at
different temperatures. At the end of the sequence, a re-analysis of the experimental results in
view of both the Boltzmann and Clausius definitions of entropy reveals some limits of the toy model,
but also allows fo…