Nine secondary school teachers participated in a five day training program where they developed inquiry-based pedagogical interventions for their science classes. Student interest and self-concept in school science and technology were measured before and after the interventions. Increases in interest and self-concept were compared with the results obtained from control groups. Results show a significant increase interest of moderate magnitude compared with the control condition, but no effect on self-concept. Our interpretation supports the use of inquiry based interventions for science classes but also presents some of the challenges faced when developing them.