Pre-service science teachers learn about metacognitive knowledge theoretically in their pedagogy courses; however, teaching practice in science classes reveals the theory-practice gap in their metacognitive knowledge, which has practical importance for prospective teachers. This paper reports on an experiment conducted to investigate the influence of self-metacognitive questioning for non-routine quantum physics problems on pre-service science teachers' attitudes towards a quantum physics course. Pre-service teacher participants in the experimental and control groups were taught the subjects of quantum physics for 14 weeks, but only those in the experimental group were guided by self-metacognitive questioning during their engagement of non-routine problem-solving as a treatment process. The results indicate that self-metacognitive questioning for non-routine quantum physics problems creates a statistical effect favouring the experimental group students' attitudes towards the quantum physics course. However, the positive change in the control group is explained by the postulates of the Elaboration Likelihood Model (ELM) of persuasion.