The aim of Nefreduca project was to develop digital science materials for chronically ill children and to assist them to cope more rationally with their illness. The Nefreduca system was developed in 2 stages.The first was a teaching-learning sequence about nutrition and kidney function, which was tested with the students and their teachers from the hospital school. The second phase was the construction of an automatic feedback system for Nefreduca. This paper reports the findings from both phases and makes the case that good feedback models must build upon on a good learning design that addresses students' misconceptions and introduces well structured e-activitie