Several international reports promote the use of the inquiry teaching methodology for improvements in science education at elementary school. Nevertheless, research indicates that pre-service elementary teachers have insufficient experience with this methodology and when they try to implement it, the theory they learnt in their university education clashes with the classroom practice they observe, a problem that has also been noted with other innovative methodologies. So, it appears essential for pre-service teachers to conduct supportive reflective practice during their education to integrate theory and practice, which various studies suggest is not usually done. Our study shows how opening up a third discursive space can assist this supportive reflective practice. The third discursive space appears when pre-service teachers are involved in specific activities that allow them to contrast the discourses of theoretical knowledge taught at university with practical knowledge arising from their ideas on science and science teaching and their observations during classroom practice. The case study of three pre-service teachers shows that this strategy was fundamental in helping them to integrate theory and practice, resulting in a better understanding of the inquiry methodology and its application in the classroom.