For more than 20 years, I'm conducting research studies in the field of Dynamic Geometry and Technology Enhanced Learning in Mathematics. The difficulties of technology integration into primary school teachers’ practices questioned the role and place of digital technology in the teachers’ system of resources. I'm studying this question by considering a duo of artefacts, composed of a tangible and a digital tool, as a simplified model of a system of instruments in a didactical situation. It enables to frame research questions related to teachers’ resources, design, quality and appropriation as well as to students’ learning in the domains of arithmetic or geometry. My approach is also relevant to deal with emergent fields of questions about robots and connected objects for education.