This work is supported by national funds through FCT - Foundation for Science and Technology, I. P., in the context of the project PTDC/CED-EDG/32422/2017. This paper aims to investigate a way of integrating mathematics, science and technology in primary school, which is considered critical to better prepare students for the real-life challenges of modern world. To achieve this purpose, it is necessary to innovate teachers' practices being crucial to promote their professional development. This study employs the case study of two teachers who participated in a continuing professional development programme developed by the authors of this paper. With a qualitative methodology and an interpretative approach, it was verified that teachers were able to innovate their practices revealing knowledge and skills to create and develop mathematical interdisciplinary tasks in class with their students. In addition, teachers recognized impact on their students and that these practices promoted their interest to learn these subject matters. We argue that it was a collaborative context between teachers with the support of the educators that gave the teachers knowledge and skills to be able to develop this approach in class. We conclude that it is possible to promote interdisciplinarity with mathematics, science and technology in the context of a collaborative teachers' professional development programme. publishersversion published