Effective reasoning about electric circuits requires a solid understanding of voltage and potential. However, most students fail to correctly analyze electric circuits as they tend to reason exclusively with current and resistance. To address these difficulties, a new curriculum based on the electron gas model was developed and empirically evaluated in a study with 790 students from Frankfurt, Germany. The study follows a pretest-posttest-control-group design and uses a recognized two-tier

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... ostic test instrument, which also allows evaluating common alternative conceptions. The results of the diagnostic assessment are very promising; students taught according to the new curriculum not only develop a significantly better conceptual understanding of voltage, but also show achievement gains of about twice that of their traditionally taught peers.