In light of extensive research demonstrating widespread misconceptions about electricity, this paper describes a learning study that targeted the most likely source of difficulty--failure of middle school pupils to develop a mental model that serves as a bridge between static and current electricity. During the intervention, pupils first envision static electricity as due to mechanical forces that separate two kinds of electrical charges. They then expand the model to account for current electricity, noting that the battery uses chemical means to separate charges, thus providing a force to drive an electric current. Pupils also develop a nuanced understanding of the role played by insulators and conductors in static and current electricity. The instructional unit combines hands-on activities and demonstrations in which pupils' pre-instructional ideas conflict with their observations, discussions to help them resolve the conflicts, and direct instruction about the history of electrical science. The underlying philosophy is constructivist--to help pupils develop a meaningful and flexible mental model of electrical phenomena.