[Objective] The aim is to explore how in-service teachers professionally view curricular materials and students' mathematical thinking in the area of measurement. [Methodology] The participants were 18 in-service primary school teachers, who completed a 12-item questionnaire with three focuses: (i) interpret students' mathematical thinking, (ii) propose activities to support students' understanding, and (iii) analyze activities related to curriculum references regarding magnitudes and their measurements. The analysis was conducted in two stages. In the first stage, the characteristics of the responses by in-service teachers to each of the items were identified, and in the second stage those characteristics were grouped according to the three focuses in order to identify any peculiarities on how teachers interpreted students' mathematical thinking and proposed and analyzed activities using the curriculum. [Results] Results indicate that teachers have difficulties in identifying errors because they do not consider the real context of the problem. Furthermore, although they were able to propose different activities, they had difficulties when asked to place the activity into an everyday context. The curricular difference between mathematical process and ability proved to be difficult for teachers in the area of measurement. [Conclusions] Teachers’ limitations show the need to develop continuing education proposals for in-service primary teachers that foster the development of teaching competences.