The aim of the present research was to determine to what extent the teaching resource designed in the context of Physical Education in 4th grade fostered mathematical competence development in the students. For the didactic intervention, a program was designed that presented the students with contextualized problem situations in Physical Education environments. Sixty-eight students were asked to design and implement a plan to solve the proposed situations using their mathematical knowledge and working cooperatively. A case study was designed, yielding quantitative-qualitative results. Data were collected through participant observation, field notes, questionnaires and interviews. The results showed that the students applied competence mathematical skills at medium-to-high performance levels. This learning evidence was supported by the fact that the students recognised the mathematical contents learnt and the role of mathematics in Physical Education. In addition, the mathematics teachers observed good command of content that had not been addressed in class.