Many studies deal with the use of simulations for scientific discovery learning, when the main task of the learner is to infer the characteristics of the model underlying the simulation (a recent review is presented by de Jong & van Joolingen, 1998). These studies deal with the problems encount-ered in simulationbased learning, with supplementary methods of supporting the learners’ discovery process and with the difficulties of evaluating and differentiating the specific outcomes. Simulation-based learning is usually regarded as an alternative approach to expository instruction or to real hands-on lab exploration, while the studies compare the outcomes of one approach over the other. In the domain of electric circuits, no difference was found between simulation-based learning and expository teaching or hands-on activities, though in the detailed analysis students from the simulation groups seemed to show more advanced mental models (Carlsen & Andre, 1992; Chambers et al., 1994). Various studies indicate that providing learners with specific assignments in combination with the simulation may have a beneficial effect on the learning outcome. The aim of this study was to examine the role of a simulation as a potential aid that may help students to bridge the gap between theory and reality in the case of electric circuits. For this purpose, simulation was used as an intermediate medium, in conjunction with a both the real phenomenon and its diagrammatic representation (Ronen & Eliahu, 1997a).