This paper describes a methodology for students to learn how to design an experiment in their first electric circuits laboratory course. It focuses on, the process students would use to design and conduct experiments when experimental error or inaccuracies in the physical model cannot be ignored. Students learn that understanding and minimizing discrepancies between theoretical models and laboratory results becomes an iterative learning process. At the completion of any cycle, the current discrepancies between the current model-i.e., hypothesis-and the experimental results are known. A new hypothesis is then constructed which is intended to explain these discrepancies. In turn, a new set of experiments is designed to test the validity of this new hypothesis. Knowledge acquired by students during one cycle is then used to guide the student-learning process in the next cycle. The ultimate goal is not to ensure that no discrepancies exist but rather that the student adequately understands their origin and that a plan could be implemented to reduce them still further if necessary.