The research project partly presented in this paper aims at investigating the potential of the design of learning environments based on research to enhance language for mathematics learning in order to foster conceptual and language development. In this paper I present a collaboratively designed learning environment on angles, with a focus on enhancing classroom discourse to adapt to the conceptual development of most students in 6th grade. The theoretical background of the research combines Vygotskian and Bakhtinian points of view on language, and relies on the idea of a secondarising process of discourse. An empirical investigation of the enacted learning environment revealed its potential to enhance classroom discourse and students' conceptual and language development by introducing an explicit distinction between empirical and theoretical aspects of measurement concepts. The findings include the identification of conditions and limitations to be addressed in the design and instructional practices of mathematics- and language-integrated interventions, in general, and for the next steps of the current project.