The focus of this paper is on the methodological approach in a design research study. The aim of the study is to explore how primary mathematics teachers coordinate mathematical and relational proficiencies for education to make the mathematical content accessible for every student. The researcher together with the participating teachers (n=5) identified the existing and desired teaching situation in two mathematical classrooms. An intervention was implemented and documented by observations, video recordings and interviews with the teachers and the students. The intervention explored the interactions between the teachers and the students, to explain possibilities of how students can be given access to the mathematical content.