The paper discusses the results of a research project based on the field testing of a course aimed at developing arithmetic problem solving skills in primary school pupils. The course was designed to incorporate e-learning techniques, including the use of ARI@ITALES authoring tools. These tools allowed the integration in the course of constructivist activities based on interaction with a set of different microworlds. The aims of the project were twofold: to analyse how the adopted approach and tools could help the teacher design and manage classroom activities integrating technology; and to evaluate the effectiveness of the ARI@ITALES tools for supporting pupils' acquisition of mathematical skills. (Contains 2 tables and 2 figures.)