Approach to the early childhood education teacher’s specialised knowledge about length and its measurement in a collaborative context of professional development

Background: to teach mathematics in early childhood education, we consider that solid and rigorous knowledge is needed. Researchers in mathematics education call for the characterisation of this specialised knowledge. Objectives: to advance in characterising the knowledge that the early childhood education teacher needs to design and implement activities on length and its measurement. Design: considering the mathematics teachers’ specialised knowledge analytical model and starting from a review of the literature on length measurement teaching in early childhood education, we approach using a qualitative and interpretative methodology, the specialised knowledge of the early childhood education teacher from two angles: the knowledge that educators-researchers consider that the teacher needs to mobilise to design the activity, and the knowledge mobilised by teachers when they reflect on that activity. Settings and participants: the research took place in 2019 in a context of collaborative professional development with four educators and two teachers. Data collection and analysis: the collaborative sessions were recorded on video. All analyses were triangulated by the authors of the study. Results: teachers’ educators give importance to mathematical knowledge of the contents and teaching-learning theories. Teachers’ reflections always start from the students’ characteristics and actions, including the emotional aspects. Conclusions: working together enriches both groups and allows to characterise the knowledge by interweaving theoretical and formal elements with intuitive and empirical elements, which improves the initial education of the early childhood teacher