The lack of conceptual understanding that results from traditional physics instruction is a phenomenon that has been well documented by the physics education community. A commonly suggested explanation for this is that the emphasis physics curricula place on quantitative problems disincentivises qualitative understanding and the development of conceptual models. This action research intervention examines the effect of pedagogies which emphasise qualitative reasoning on conceptual understanding, attitudes towards physics and problem-solving confidence. Following a seven-lesson sequence on electric circuits with a Year 12 class, significant improvements in conceptual understanding were observed. The prevalence of common misconceptions decreased, and performance on conceptual questions increased. No significant change in students’ attitudes or confidence was observed.