Understanding electrical circuits can be difficult for novices of all ages. In this paper, we describe a science museum exhibit that enables visitors to make circuits on an interactive tabletop and observe a simulation of electrons flowing through the circuit. Our goal is to use multiple representations to help convey basic concepts of current and resistance. To study visitor interaction and learning, we tested the design at a popular science museum with 60 parent-child dyads in three conditions: a control condition with no electron simulation; a condition with the simulation displayed alongside the circuit on the same screen; and an augmented reality condition, with the simulation displayed on a tablet that acts as a lens to see into the circuit. Our findings show that children did significantly better on a posttest in both experimental conditions, with children performing best in the AR condition. However, analysis of session videos shows unexpected parent-child collaboration in the AR condition.