Students' difficulties in learning of mathematics have for a long time, been investigated by researchers in different fields. Within educational research there are claims that technological tools appropriately integrated in students' mathematical work can support their understanding of a wide range of concepts in mathematics. This paper reports on the initial investigation for the design of Interactive Learning Environments (ILE) to support students' learning of mathematics. The project is guided by the notion of Design Based Research (DBR) and aims to explore how to design ILE that support students' understanding of integrals in particular. The initial study was conducted at a Swedish university with 10 students in 4 groups. The study confirmed difficulties in students' understanding of integrals as reported in educational literature and provides a set of design aims for the next iteration of the ILE to support the learning.