This paper presents the results of the case study introducing TRAKLA2 system in the course of data structures and algorithms at the University of Turku in 2004. We compared students’ learning results with the results of the previous year. The numerical course results were clearly better than in 2003 when only pen-and-paper type exercises in classrooms were used. In addition, a survey was made with over 100 students on the changes in their attitudes towards web-based learning environments while getting acquainted with a wholly new system providing them automatic feedback and the option to resubmit their solutions. Our results show that such an on-line learning environment considerably increases positive attitudes towards web-based learning, and according to students’ self-evaluations, the best learning results are achieved by combining traditional teaching and www-based learning.