This paper presents a new construct: the conceptual tool ‘Flexibility’. The construct was a result of an attempt to extract experiences of teaching and learning with the use of laptops. It was further developed and refined on the basis of four small-scale teaching experiments. The teaching experiments, being part of a development project in upper secondary school mathematics, investigated the use of laptops for teaching differential equations from a modeling point of view. The research was double-aimed: one objective was to conclude the project with some recommendations for the design of teaching, in the form of guidelines suitable for a wider dissemination amongst upper secondary mathematics teachers. The other main aim was to draw on the project’s experiences for theory development within a framework based on Realistic Mathematics Education (RME) and related ideas. The construction of ‘Flexibility’ served both these aims
