The progress achieved in the models used by future Spanish primary school teachers on the phenomenon of tides is analysed after implementing a modelling-based didactic sequence. It was implemented throughout ten sessions in two classes (N = 88). An open-ended questionnaire was used as a data collecting instrument. Based on prior studies and the information gathered in this instrument, a holistic rubric was created to characterise the models used before and after implementing the didactic sequence. The comparison of the results obtained reveals important advances in the models used, which shows the usefulness of the sequence taking into account the progression of the students' knowledge of the phenomenon analysed. However, it also reflects the persistence of some difficulties that hinder the achievement of the desired school model. The main difficulty lay in understanding the effect produced by the differential forces on a flexible body, such as the oceanic mass. All this helps identify possible improvements in the design process of the didactic sequence developed, such as introducing new activities to reinforce key concepts, reordering some activities, and enhancing the role of thought experiments.